code: public WikiFormat removeStyle(WikiStyle style)
      {
          if (!fStyles.contains(style)) {
              return this;
          }
          WikiFormat clone = getClone();
          clone.fStyles.remove(style);
          return clone;
      }
docs: Creates a new style set which does not contain the specified style.
  
  @param style the style to add
  @return a new copy of the style set containing the given style