code: public Message clearFlag(Flag ... flags) {
          if(flags != null) {
              short tmp=this.flags;
              for(Flag flag : flags)
                  if(flag != null)
                      tmp&=~flag.value();
              this.flags=tmp;
          }
          return this;
      }
docs: Clears a number of flags in a message
  @param flags The flags
  @return A reference to the message