history length = 1
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 0
      length: 4
      span_id: 0
      line: (SourceLine line_num:1 content:'echo ${two:-}' src:(source.MainFile path:'<test_lib>'))
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (braced_var_sub
      left: 
        (Token
          id: Id.Left_DollarBrace
          col: 5
          length: 2
          span_id: 2
          line: 
            (SourceLine
              line_num: 1
              content: 'echo ${two:-}'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '${'
        )
      token: 
        (Token
          id: Id.VSub_Name
          col: 7
          length: 3
          span_id: 3
          line: 
            (SourceLine
              line_num: 1
              content: 'echo ${two:-}'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: two
        )
      var_name: two
      suffix_op: 
        (suffix_op.Unary
          op: 
            (Token
              id: Id.VTest_ColonHyphen
              col: 10
              length: 2
              span_id: 4
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo ${two:-}'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          arg_word: (compound_word parts:[])
        )
      right: 
        (Token
          id: Id.Right_DollarBrace
          col: 12
          length: 1
          span_id: 5
          line: 
            (SourceLine
              line_num: 1
              content: 'echo ${two:-}'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '}'
        )
    )
  ]
)]
! echo ${two:-}
history length = 1
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 0
      length: 4
      span_id: 7
      line: (SourceLine line_num:1 content:'echo ${two:-}' src:(source.MainFile path:'<test_lib>'))
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (braced_var_sub
      left: 
        (Token
          id: Id.Left_DollarBrace
          col: 5
          length: 2
          span_id: 9
          line: 
            (SourceLine
              line_num: 1
              content: 'echo ${two:-}'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '${'
        )
      token: 
        (Token
          id: Id.VSub_Name
          col: 7
          length: 3
          span_id: 10
          line: 
            (SourceLine
              line_num: 1
              content: 'echo ${two:-}'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: two
        )
      var_name: two
      suffix_op: 
        (suffix_op.Unary
          op: 
            (Token
              id: Id.VTest_ColonHyphen
              col: 10
              length: 2
              span_id: 11
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo ${two:-}'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          arg_word: (compound_word parts:[])
        )
      right: 
        (Token
          id: Id.Right_DollarBrace
          col: 12
          length: 1
          span_id: 12
          line: 
            (SourceLine
              line_num: 1
              content: 'echo ${two:-}'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '}'
        )
    )
  ]
)]
.! echo 'hi#'${two:-}
history length = 1
Couldn't parse historical command '(': 
TRAIL words: []
history length = 1
Couldn't parse historical command 'a( )': 
TRAIL words: []
.history length = 1
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 10
      length: 2
      span_id: 6
      line: (SourceLine line_num:1 content:'echo hi | wc -l' src:(source.MainFile path:'<test_lib>'))
      tval: wc
    )
  ]
), (compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 13
      length: 2
      span_id: 8
      line: (SourceLine line_num:1 content:'echo hi | wc -l' src:(source.MainFile path:'<test_lib>'))
      tval: -l
    )
  ]
)]
! echo -l
history length = 1
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 19
      length: 4
      span_id: 15
      line: 
        (SourceLine
          line_num: 1
          content: 'for i in 1 2 3; do echo xx; done'
          src: (source.MainFile path:'<test_lib>')
        )
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 24
      length: 2
      span_id: 17
      line: 
        (SourceLine
          line_num: 1
          content: 'for i in 1 2 3; do echo xx; done'
          src: (source.MainFile path:'<test_lib>')
        )
      tval: xx
    )
  ]
)]
! echo xx
history length = 1
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 2
      length: 4
      span_id: 2
      line: (SourceLine line_num:1 content:'{ echo yy; }' src:(source.MainFile path:'<test_lib>'))
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 7
      length: 2
      span_id: 4
      line: (SourceLine line_num:1 content:'{ echo yy; }' src:(source.MainFile path:'<test_lib>'))
      tval: yy
    )
  ]
)]
.! echo yy
history length = 2
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 0
      length: 4
      span_id: 0
      line: 
        (SourceLine
          line_num: 1
          content: 'echo $three ${4:-} "${five@P}"'
          src: (source.MainFile path:'<test_lib>')
        )
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (simple_var_sub
      left: 
        (Token
          id: Id.VSub_DollarName
          col: 5
          length: 6
          span_id: 2
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '$three'
        )
      var_name: three
    )
  ]
), (compound_word
  parts: [
    (braced_var_sub
      left: 
        (Token
          id: Id.Left_DollarBrace
          col: 12
          length: 2
          span_id: 4
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '${'
        )
      token: 
        (Token
          id: Id.VSub_Number
          col: 14
          length: 1
          span_id: 5
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: 4
        )
      var_name: 4
      suffix_op: 
        (suffix_op.Unary
          op: 
            (Token
              id: Id.VTest_ColonHyphen
              col: 15
              length: 2
              span_id: 6
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          arg_word: (compound_word parts:[])
        )
      right: 
        (Token
          id: Id.Right_DollarBrace
          col: 17
          length: 1
          span_id: 7
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '}'
        )
    )
  ]
), (compound_word
  parts: [
    (double_quoted
      left: 
        (Token
          id: Id.Left_DoubleQuote
          col: 19
          length: 1
          span_id: 9
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '"'
        )
      parts: [
        (braced_var_sub
          left: 
            (Token
              id: Id.Left_DollarBrace
              col: 20
              length: 2
              span_id: 10
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: '${'
            )
          token: 
            (Token
              id: Id.VSub_Name
              col: 22
              length: 4
              span_id: 11
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: five
            )
          var_name: five
          suffix_op: 
            (Token
              id: Id.VOp0_P
              col: 26
              length: 2
              span_id: 12
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          right: 
            (Token
              id: Id.Right_DollarBrace
              col: 28
              length: 1
              span_id: 13
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: '}'
            )
        )
      ]
      right: 
        (Token
          id: Id.Right_DoubleQuote
          col: 29
          length: 1
          span_id: 14
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '"'
        )
    )
  ]
)]
! echo "${five@P}"
history length = 2
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 0
      length: 4
      span_id: 16
      line: 
        (SourceLine
          line_num: 1
          content: 'echo $three ${4:-} "${five@P}"'
          src: (source.MainFile path:'<test_lib>')
        )
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (simple_var_sub
      left: 
        (Token
          id: Id.VSub_DollarName
          col: 5
          length: 6
          span_id: 18
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '$three'
        )
      var_name: three
    )
  ]
), (compound_word
  parts: [
    (braced_var_sub
      left: 
        (Token
          id: Id.Left_DollarBrace
          col: 12
          length: 2
          span_id: 20
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '${'
        )
      token: 
        (Token
          id: Id.VSub_Number
          col: 14
          length: 1
          span_id: 21
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: 4
        )
      var_name: 4
      suffix_op: 
        (suffix_op.Unary
          op: 
            (Token
              id: Id.VTest_ColonHyphen
              col: 15
              length: 2
              span_id: 22
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          arg_word: (compound_word parts:[])
        )
      right: 
        (Token
          id: Id.Right_DollarBrace
          col: 17
          length: 1
          span_id: 23
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '}'
        )
    )
  ]
), (compound_word
  parts: [
    (double_quoted
      left: 
        (Token
          id: Id.Left_DoubleQuote
          col: 19
          length: 1
          span_id: 25
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '"'
        )
      parts: [
        (braced_var_sub
          left: 
            (Token
              id: Id.Left_DollarBrace
              col: 20
              length: 2
              span_id: 26
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: '${'
            )
          token: 
            (Token
              id: Id.VSub_Name
              col: 22
              length: 4
              span_id: 27
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: five
            )
          var_name: five
          suffix_op: 
            (Token
              id: Id.VOp0_P
              col: 26
              length: 2
              span_id: 28
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          right: 
            (Token
              id: Id.Right_DollarBrace
              col: 28
              length: 1
              span_id: 29
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: '}'
            )
        )
      ]
      right: 
        (Token
          id: Id.Right_DoubleQuote
          col: 29
          length: 1
          span_id: 30
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '"'
        )
    )
  ]
)]
! echo $three
history length = 2
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 0
      length: 4
      span_id: 32
      line: 
        (SourceLine
          line_num: 1
          content: 'echo $three ${4:-} "${five@P}"'
          src: (source.MainFile path:'<test_lib>')
        )
      tval: echo
    )
  ]
), (compound_word
  parts: [
    (simple_var_sub
      left: 
        (Token
          id: Id.VSub_DollarName
          col: 5
          length: 6
          span_id: 34
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '$three'
        )
      var_name: three
    )
  ]
), (compound_word
  parts: [
    (braced_var_sub
      left: 
        (Token
          id: Id.Left_DollarBrace
          col: 12
          length: 2
          span_id: 36
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '${'
        )
      token: 
        (Token
          id: Id.VSub_Number
          col: 14
          length: 1
          span_id: 37
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: 4
        )
      var_name: 4
      suffix_op: 
        (suffix_op.Unary
          op: 
            (Token
              id: Id.VTest_ColonHyphen
              col: 15
              length: 2
              span_id: 38
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          arg_word: (compound_word parts:[])
        )
      right: 
        (Token
          id: Id.Right_DollarBrace
          col: 17
          length: 1
          span_id: 39
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '}'
        )
    )
  ]
), (compound_word
  parts: [
    (double_quoted
      left: 
        (Token
          id: Id.Left_DoubleQuote
          col: 19
          length: 1
          span_id: 41
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '"'
        )
      parts: [
        (braced_var_sub
          left: 
            (Token
              id: Id.Left_DollarBrace
              col: 20
              length: 2
              span_id: 42
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: '${'
            )
          token: 
            (Token
              id: Id.VSub_Name
              col: 22
              length: 4
              span_id: 43
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: five
            )
          var_name: five
          suffix_op: 
            (Token
              id: Id.VOp0_P
              col: 26
              length: 2
              span_id: 44
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: _
            )
          right: 
            (Token
              id: Id.Right_DollarBrace
              col: 28
              length: 1
              span_id: 45
              line: 
                (SourceLine
                  line_num: 1
                  content: 'echo $three ${4:-} "${five@P}"'
                  src: (source.MainFile path:'<test_lib>')
                )
              tval: '}'
            )
        )
      ]
      right: 
        (Token
          id: Id.Right_DoubleQuote
          col: 29
          length: 1
          span_id: 46
          line: 
            (SourceLine
              line_num: 1
              content: 'echo $three ${4:-} "${five@P}"'
              src: (source.MainFile path:'<test_lib>')
            )
          tval: '"'
        )
    )
  ]
)]
.! echo -n $three ${4:-} "${five@P}"
history length = 3
! echo ${two:-}

history length = 3
! echo ${two:-} 
history length = 3
! echo 1
history length = 3
! ls /echo/
history length = 3
! echo ${two:-}
history length = 3
history length = 3
history length = 3
! ls /echo/
history length = 3
TRAIL words: [(compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 0
      length: 2
      span_id: 0
      line: (SourceLine line_num:1 content:'ls /echo/' src:(source.MainFile path:'<test_lib>'))
      tval: ls
    )
  ]
), (compound_word
  parts: [
    (Token
      id: Id.Lit_Chars
      col: 3
      length: 6
      span_id: 2
      line: (SourceLine line_num:1 content:'ls /echo/' src:(source.MainFile path:'<test_lib>'))
      tval: '/echo/'
    )
  ]
)]
.
----------------------------------------------------------------------
Ran 5 tests in 0.039s

OK
! echo /echo/