(CommandList
  children: [
    (If
      arms: [
        (if_arm
          cond: [
            (Sentence
              child: (C {(Lit_Other "[")} {($ VSub_Pound "$#")} {(-ne)} {(2)} {(Lit_Other "]")})
              terminator: <Op_Semi ";">
            )
          ]
          action: [
            (SimpleCommand
              words: [{(echo)} {(DQ ("Usage ") ($ VSub_Number "$0") (" from to"))}]
              redirects: [(Redir op_id:Redir_GreatAnd fd:-1 arg_word:{(2)} spids:[39])]
            )
            (SimpleCommand
              words: [{(echo)} {(DQ ("for e.g. ") ($ VSub_Number "$0") (" '2 grams' drams"))}]
              redirects: [(Redir op_id:Redir_GreatAnd fd:-1 arg_word:{(2)} spids:[51])]
            )
            (C {(exit)})
          ]
          spids: [-1 28]
        )
      ]
      spids: [-1 57]
    )
    (C {(units)} {(-t)} {(DQ ($ VSub_Number "$1"))} {(DQ ($ VSub_Number "$2"))})
  ]
)