Example of how lambdas can generally be refactored into something more readable.

gistfile1.py

# using lambdas
def signed_in_both_chambers(self, **kwargs):
    signed = lambda a: 'Signed in the %s' % a
    return (self.filter(models.Q(bill_type='SB') | models.Q(bill_type='HB'))
            .filter(actions__description=signed('House'))
            .filter(actions__description=signed('Senate')))

# refactored into these methods
def has_action(self, action):
    """Filter QuerySet by a given action"""
    return self.filter(actions__description=action)

def bills_from_both_chambers(self):
    """Return all House and Senate bills"""
    return self.filter(models.Q(bill_type='SB') | models.Q(bill_type='HB'))

def signed_in_chamber(self, chamber):
    """Filter for bills that have been signed in a given chamber"""
    action = 'Signed in the %s' % chamber.title()
    return self.has_action(action)

def signed_in_both_chambers(self):
    """Return all bills that have passed both chambers"""
    return (self.bills_from_both_chambers()
            .signed_in_chamber('House')
            .signed_in_chamber('Senate'))

Hmm... guess I should do something with those kwargs, huh? :-)

I just added has_action after adding another couple of methods that do that same actions__description=foo code. The original refactor was just bills_from_both_chambers and a simple version of signed_in_chamber. The benefit of the refactoring is that now I can pull just bills or bills signed in a given chamber. The original method has everything locked up in one method.