code: def get_one(self, criteria):
          ''' return one item
          '''
          try:
              items = [item for item in self._get_with_criteria(criteria, limit=1)]
              return items[0]
          except:
              return Nonf get_one(self, criteria):
          ''' return one item
          '''
          try:
              items = [item for item in self._get_with_criteria(criteria, limit=1)]
              return items[0]
          except:
              return None
docs: return one item