SOURCE_FILE@0..17
  FN@0..17
    FN_KW@0..2 "fn"
    WHITESPACE@2..3 " "
    NAME@3..4
      IDENT@3..4 "f"
    PARAM_LIST@4..14
      L_PAREN@4..5 "("
      PARAM@5..13
        WILDCARD_PAT@5..6
          UNDERSCORE@5..6 "_"
        COLON@6..7 ":"
        WHITESPACE@7..8 " "
        REF_TYPE@8..13
          AMP@8..9 "&"
          IMPL_TRAIT_TYPE@9..13
            IMPL_KW@9..13 "impl"
            TYPE_BOUND_LIST@13..13
      R_PAREN@13..14 ")"
    WHITESPACE@14..15 " "
    BLOCK_EXPR@15..17
      STMT_LIST@15..17
        L_CURLY@15..16 "{"
        R_CURLY@16..17 "}"
error 9..13: At least one trait is required for an object type