for it in iterablesfor in ityield combinations(iterablercreates an iterator that returns all -length subsequences of items taken from iterable the items in the returned subsequences are ordered in the same way in which they were ordered in the input iterable for exampleif iterable is the list [ , , , ]the sequence produced by combinations([ , , , ] is [ , ][ , ][ , ][ , ][ , count([ ]creates an iterator that produces consecutive integers starting with if is omittedcounting starts at (note that this iterator does not support long integers if sys maxint is exceededthe counter overflows and continues to count starting with -sys maxint cycle(iterablecreates an iterator that cycles over the elements in iterable over and over again internallya copy of the elements in iterable is made this copy is used to return the repeated items in the cycle dropwhile(predicateiterablecreates an iterator that discards items from iterable as long as the function predicate(itemis true once predicate returns falsethat item and all subsequent items in iterable are produced groupby(iterable [key]creates an iterator that groups consecutive items produced by iterable the grouping process works by looking for duplicate items for instanceif iterable produces the same item on several consecutive iterationsthat defines group if this is applied to sorted listthe groups would define all the unique items in the list keyif suppliedis function that is applied to each item if presentthe return value of this function is used to compare successive items instead of the items themselves the iterator returned by this function produces tuples (keygroup)where key is the key value for the group and group is an iterator that yields all the items that made up the group ifilter(predicateiterablecreates an iterator that only produces items from iterable for which predicate(itemis true if predicate is noneall the items in iterable that evaluate as true are returned ifilterfalse(predicateiterablecreates an iterator that only produces items from iterable for which predicate(itemis false if predicate is noneall the items in iterable that evaluate as false are returned lib fl ff