code: def items_since(date_time, opts = {})
        opts = opts.clone
        unless date_time.kind_of?(Date)
          raise EwsBadArgumentError, "First argument must be a Date or DateTime"
        end
        restr = {:restriction =>
          {:is_greater_than_or_equal_to =>
            [{:field_uRI => {:field_uRI=>'item:DateTimeReceived'}},
              {:field_uRI_or_constant =>{:constant => {:value=>date_time.to_datetime}}}]
          }}
          items(opts.merge(restr))
      end
docs: Fetch items since a give DateTime
   @param [DateTime] date_time the time to fetch Items since.