def include?(event, date)
      return false unless @elems.include?(event)
      return 0<(self.select{|ev,xpr| ev.eql?(event)&&xpr.include?(date);}).size
    end
def include?(event, date)
      return false unless @elems.include?(event)
      return 0<(self.select{|ev,xpr| ev.eql?(event)&&xpr.include?(date);}).size
    end
Return true or false depend on if the supplied event is scheduled to occur on the
 given date.