This method deletes an advertised Flow Specification route.

        ``flowspec_family`` specifies one of the flowspec family name.

        ``rules`` specifies NLRIs of Flow Specification as
        a dictionary type value.

        ``route_dist`` specifies a route distinguisher value.

def flowspec_prefix_del(self, flowspec_family, rules, route_dist=None):
        """ This method deletes an advertised Flow Specification route.

        ``flowspec_family`` specifies one of the flowspec family name.

        ``rules`` specifies NLRIs of Flow Specification as
        a dictionary type value.

        ``route_dist`` specifies a route distinguisher value.
        """
        func_name = 'flowspec.del'

        # Set required arguments
        kwargs = {
            FLOWSPEC_FAMILY: flowspec_family,
            FLOWSPEC_RULES: rules,
        }

        if flowspec_family in [FLOWSPEC_FAMILY_VPNV4, FLOWSPEC_FAMILY_VPNV6,
                               FLOWSPEC_FAMILY_L2VPN]:
            func_name = 'flowspec.del_local'
            kwargs.update({ROUTE_DISTINGUISHER: route_dist})

        call(func_name, **kwargs)