@environmentfilter
def do_sum(environment, iterable, attribute=None, start=0):
 if (attribute is not None):
  iterable = imap(make_attrgetter(environment, attribute), iterable)
 return sum(iterable, start)

@ environmentfilter def do_sum ( environment , iterable , attribute = None , start = 0 ) : if ( attribute is not None ) : iterable = imap ( make_attrgetter ( environment , attribute ) , iterable ) return sum ( iterable , start )
returns the sum of a sequence of numbers plus the value of parameter start .