SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "foo"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE " "
        EXPR_STMT
          MACRO_CALL
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "try"
            BANG "!"
            TOKEN_TREE
              L_PAREN "("
              IDENT "Ok"
              TOKEN_TREE
                L_PAREN "("
                TOKEN_TREE
                  L_PAREN "("
                  R_PAREN ")"
                R_PAREN ")"
              R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE " "
        R_CURLY "}"
  WHITESPACE "\n"
