code: public Token addToTrigger(Char ch) {
          trigger += ch.getValue();
          internTrigger = null;
          source += ch.getValue();
          return this;
      }
docs: Adds the given Char to the trigger (and the source) but not to the content
  
  @param ch the character to add to the trigger and source
  @return <tt>this</tt> to support fluent method calls