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
          YIELD_EXPR
            YIELD_KW "yield"
          SEMICOLON ";"
        WHITESPACE "\n    "
        EXPR_STMT
          YIELD_EXPR
            YIELD_KW "yield"
            WHITESPACE " "
            LITERAL
              INT_NUMBER "1"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
