SOURCE_FILE@0..30
  FN_DEF@0..29
    FN_KW@0..2 "fn"
    WHITESPACE@2..3 " "
    NAME@3..6
      IDENT@3..6 "foo"
    PARAM_LIST@6..8
      L_PAREN@6..7 "("
      R_PAREN@7..8 ")"
    WHITESPACE@8..9 " "
    BLOCK_EXPR@9..29
      L_CURLY@9..10 "{"
      WHITESPACE@10..11 " "
      LET_STMT@11..27
        LET_KW@11..14 "let"
        WHITESPACE@14..15 " "
        PLACEHOLDER_PAT@15..16
          UNDERSCORE@15..16 "_"
        WHITESPACE@16..17 " "
        EQ@17..18 "="
        WHITESPACE@18..19 " "
        EFFECT_EXPR@19..27
          ASYNC_KW@19..24 "async"
          WHITESPACE@24..25 " "
          BLOCK_EXPR@25..27
            L_CURLY@25..26 "{"
            R_CURLY@26..27 "}"
      WHITESPACE@27..28 " "
      R_CURLY@28..29 "}"
  WHITESPACE@29..30 "\n"
error 27..27: expected SEMICOLON