'Return the number of networks.
The result depends on the identity
of the user making the request (as indicated by the context) as well
as any filters.
:param context: neutron api request context
:param filters: a dictionary with keys that are valid keys for
a network as listed in the
:obj:`RESOURCE_ATTRIBUTE_MAP` object
in :file:`neutron/api/v2/attributes.py`. Values in
this dictionary are an iterable containing values that
will be used for an exact match comparison for that
value.  Each result returned by this function will have
matched one of the values for each key in filters.
NOTE: this method is optional, as it was not part of the originally
defined plugin API.'

def get_networks_count(self, context, filters=None):

    raise NotImplementedError()
