SOURCE_FILE@0..16
  FN@0..16
    FN_KW@0..2 "fn"
    WHITESPACE@2..3 " "
    NAME@3..4
      IDENT@3..4 "f"
    PARAM_LIST@4..13
      L_PAREN@4..5 "("
      PARAM@5..12
        WILDCARD_PAT@5..6
          UNDERSCORE@5..6 "_"
        COLON@6..7 ":"
        WHITESPACE@7..8 " "
        IMPL_TRAIT_TYPE@8..12
          IMPL_KW@8..12 "impl"
          TYPE_BOUND_LIST@12..12
      R_PAREN@12..13 ")"
    WHITESPACE@13..14 " "
    BLOCK_EXPR@14..16
      STMT_LIST@14..16
        L_CURLY@14..15 "{"
        R_CURLY@15..16 "}"
error 8..12: At least one trait is required for an object type