code: def fetch_interfaces(self, interface, way):
          
          if not interface:
              return []
          if way == 'requires':
              request = '&requires=' + interface
          else:
              request = '&provides=' + interface
          url = (self.url + '/search?' +
                 'include=charm-metadata&include=stats&include=supported-series'
                 '&include=extra-info&include=bundle-unit-count'
                 '&limit=1000&include=owner' + request)
          data = self._get(url)
          return data.json().values()
docs: Get the list of charms that provides or requires this interface.
  
          @param interface The interface for the charm relation.
          @param way The type of relation, either "provides" or "requires".
          @return List of charms