code: def validate_version(exchange_version)
        if server_version < exchange_version
          msg = 'The operation you are attempting to use is not compatible with'
          msg << " your configured Exchange Server version(#{server_version})."
          msg << " You must be running at least version (#{exchange_version})."
          raise EwsServerVersionError, msg
        end
      end
docs: Some operations only exist for certain versions of Exchange Server.
   This method should be called with the required version and we'll throw
   an exception of the currently set @server_version does not comply.