code: def range(self, start_date=None, stop_date=None, field=lambda x: x.xfer):
          
          assert start_date <= stop_date, \
              "Start date must be earlier than end date."
  
          out = Transactions()
  
          for t in self.trans:
              date = field(t)
              if (start_date is not None) and not (date >= start_date):
                  continue
              if (stop_date is not None) and not (date <= stop_date):
                  continue
              out.append(t)
  
          return out
docs: Return a ``Transactions`` object in an inclusive date range.
  
          Args:
              start_date: A ``datetime.Date`` object that marks the inclusive
              start date for the range.
  
              stop_date: A ``datetime.Date`` object that marks the inclusive end
              date for the range.
  
              field: The field to compare start and end dates to. Default is the
              ``xfer`` field.
  
          Returns:
              A ``Transactions`` object.