code: def selections(self):
          "Yields (column, lookup, value) tuples"
          for key, value in self.pairs:
              if '__' in key:
                  column, lookup = key.rsplit('__', 1)
              else:
                  column = key
                  lookup = 'exact'
              yield column, lookup, valuf selections(self):
          "Yields (column, lookup, value) tuples"
          for key, value in self.pairs:
              if '__' in key:
                  column, lookup = key.rsplit('__', 1)
              else:
                  column = key
                  lookup = 'exact'
              yield column, lookup, value
docs: Yields (column, lookup, value) tuples