code: def get_row_generator(self, ref, cache=None):
  
          
          from inspect import isgenerator
          from rowgenerators import get_generator
  
          g = get_generator(ref)
  
          if not g:
              raise GenerateError("Cant figure out how to generate rows from {} ref: {}".format(type(ref), ref))
          else:
              return g
docs: Return a row generator for a reference