SOURCE_FILE@0..20
  FN@0..20
    FN_KW@0..2 "fn"
    WHITESPACE@2..3 " "
    NAME@3..4
      IDENT@3..4 "f"
    PARAM_LIST@4..17
      L_PAREN@4..5 "("
      PARAM@5..16
        WILDCARD_PAT@5..6
          UNDERSCORE@5..6 "_"
        COLON@6..7 ":"
        WHITESPACE@7..8 " "
        REF_TYPE@8..16
          AMP@8..9 "&"
          IMPL_TRAIT_TYPE@9..16
            IMPL_KW@9..13 "impl"
            WHITESPACE@13..14 " "
            TYPE_BOUND_LIST@14..16
              TYPE_BOUND@14..16
                LIFETIME@14..16
                  LIFETIME_IDENT@14..16 "'a"
      R_PAREN@16..17 ")"
    WHITESPACE@17..18 " "
    BLOCK_EXPR@18..20
      STMT_LIST@18..20
        L_CURLY@18..19 "{"
        R_CURLY@19..20 "}"
error 9..16: At least one trait is required for an object type