code: public Characters remove(Characters other) {
          checkArgNotNull(other, "other");
          if (!subtractive && !other.subtractive) {
              return removeFromChars(other.chars);
          }
          if (subtractive && other.subtractive) {
              return new Characters(false, other.removeFromChars(chars).chars);
          }
          return subtractive ? addToChars(other.chars) : retainAllChars(other.chars);
      }
docs: Returns a new Characters object containing all the characters of this instance minus all characters of the
  given instance.
  
  @param other the other Characters to remove
  @return a new Characters object