def __len__(self):
length = <NUM_LIT:0><EOL>for family in self.families:<EOL><INDENT>length += len(family)<EOL><DEDENT>return length<EOL>
Get total number of detections in Party.

:return: length, int

.. rubric:: Example

>>> party = Party(families=[Family(template=Template(name='a')),
...                         Family(template=Template(name='b'))])
>>> len(party)
0