SOURCE_FILE
  TYPE_ALIAS
    TYPE_KW "type"
    WHITESPACE " "
    NAME
      IDENT "X"
    WHITESPACE " "
    EQ "="
    WHITESPACE " "
    TUPLE_TYPE
      L_PAREN "("
      R_PAREN ")"
    SEMICOLON ";"
  WHITESPACE "\n\n"
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "main"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          TUPLE_PAT
            L_PAREN "("
            R_PAREN ")"
          COLON ":"
          PATH_TYPE
            PATH
              PATH_SEGMENT
                COLON2 "::"
                NAME_REF
                  IDENT "X"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"