code: def get_seq(self,obj,default=None):
          
          if is_sequence(obj):
              return obj
          if is_number(obj): return [obj]
          if obj is None and default is not None:
              log.warning('using default value (%s)'%(default))
              return self.get_seq(default)
          raise ValueError('expected sequence|number but got %s'%(type(obj)))
docs: Return sequence.