SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "foo"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        EXPR_STMT
          TUPLE_EXPR
            L_PAREN "("
            COMMA ","
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n    "
        EXPR_STMT
          TUPLE_EXPR
            L_PAREN "("
            PATH_EXPR
              PATH
                PATH_SEGMENT
                  NAME_REF
                    IDENT "a"
            COMMA ","
            WHITESPACE " "
            COMMA ","
            WHITESPACE " "
            PATH_EXPR
              PATH
                PATH_SEGMENT
                  NAME_REF
                    IDENT "b"
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
error 16: expected expression
error 27: expected expression
