code: public Signature insertArgs(String beforeName, String[] names, Class<?>... types) {
          return insertArgs(argOffset(beforeName), names, types);
      }
docs: Insert arguments (names + types) into the signature before the argument
  with the given name.
  
  @param beforeName the name of the argument before which to insert
  @param names      the names of the new arguments
  @param types      the types of the new arguments
  @return a new Signature with the added arguments