def extend ( self , iterable ) : return super ( Collection , self ) . extend ( self . _ensure_iterable_is_valid ( iterable ) )
'collection' object is not iterable python
Extend the list by appending all the items in the given list .
def extend(self, iterable):
        """Extend the list by appending all the items in the given list."""
        return super(Collection, self).extend(
            self._ensure_iterable_is_valid(iterable))