docs: def get_asset(self, asset_id=None):
          """Gets the ``Asset`` specified by its ``Id``.
  
          In plenary mode, the exact ``Id`` is found or a ``NotFound``
          results. Otherwise, the returned ``Asset`` may have a different
          ``Id`` than requested, such as the case where a duplicate ``Id``
          was assigned to an ``Asset`` and retained for compatibility.
  
          :param asset_id: the ``Id`` of the ``Asset`` to retrieve
          :type asset_id: ``osid.id.Id``
          :return: the returned ``Asset``
          :rtype: ``osid.repository.Asset``
          :raise: ``NotFound`` -- no ``Asset`` found with the given ``Id``
          :raise: ``NullArgument`` -- ``asset_id`` is ``null``
          :raise: ``OperationFailed`` -- unable to complete request
          :raise: ``PermissionDenied`` -- authorization failure
  
          *compliance: mandatory -- This method must be implemented.*
  
          """
          if asset_id is None:
              raise NullArgument()
          url_path = construct_url('assets',
                                   bank_id=self._catalog_idstr,
                                   asset_id=asset_id)
          return objects.Asset(self._get_request(url_path))