SOURCE_FILE
  STRUCT
    STRUCT_KW "struct"
    WHITESPACE " "
    NAME
      IDENT "X"
    WHITESPACE " "
    RECORD_FIELD_LIST
      L_CURLY "{"
      RECORD_FIELD
        NAME
          IDENT "a"
        COLON ":"
        WHITESPACE " "
        PATH_TYPE
          PATH
            PATH_SEGMENT
              NAME_REF
                IDENT "i32"
      R_CURLY "}"
  WHITESPACE "\n"
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "f"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          IDENT_PAT
            NAME
              IDENT "foo"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          RECORD_EXPR
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "X"
            WHITESPACE " "
            RECORD_EXPR_FIELD_LIST
              L_CURLY "{"
              WHITESPACE "\n        "
              RECORD_EXPR_FIELD
                NAME_REF
                  IDENT "a"
                COLON ":"
                WHITESPACE " "
                LITERAL
                  INT_NUMBER "1"
              WHITESPACE "\n    "
              R_CURLY "}"
          WHITESPACE " "
          LET_ELSE
            ELSE_KW "else"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                WHITESPACE "\n        "
                EXPR_STMT
                  RETURN_EXPR
                    RETURN_KW "return"
                  SEMICOLON ";"
                WHITESPACE "\n    "
                R_CURLY "}"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
error 63: right curly brace `}` before `else` in a `let...else` statement not allowed
