message: Use Lark's priorities to disambiguate
  Previously, the parser would nondeterministically pick between parsing
  `const` correctly and parsing it as an operator (when the constant could
  also be interpreted as an identifier, like "true").
diff: @@ -7,9 +7,11 @@ start: func*
  func: CNAME "{" instr* "}"
  -instr: IDENT "=" "const" lit -> const
  - | IDENT "=" CNAME IDENT* -> op
  - | IDENT ":" -> label
  +?instr: const | op | label
  +
  +const.3: IDENT "=" "const" lit
  +op.2: IDENT "=" CNAME IDENT*
  +label.1: IDENT ":"
  lit: NUMBER -> int
  | BOOL -> bool
  