code: public int argOffsets(String pattern) {
          for (int i = 0; i < argNames.length; i++) {
              if (Pattern.compile(pattern).matcher(argNames[i]).find()) return i;
          }
          return -1;
      }
docs: Retrieve the offset of the given argument name in this signature's
  arguments. If the argument name is not in the argument list, returns -1.
  
  @param pattern the argument name to search for
  @return the offset at which the argument name was found or -1