def get_source_variable(self, source_id, variable):
        """ Get the current value of a source variable. If the variable is not
        in the cache it will be retrieved from the controller. """

        source_id = int(source_id)
        try:
            return self._retrieve_cached_source_variable(
                    source_id, variable)
        except UncachedVariable:
            return (yield from self._send_cmd("GET S[%d].%s" % (
                source_id, variable)))
def get_source_variable ( self , source_id , variable ) : source_id = int ( source_id ) try : return self . _retrieve_cached_source_variable ( source_id , variable ) except UncachedVariable : return ( yield from self . _send_cmd ( "GET S[%d].%s" % ( source_id , variable ) ) )
Get the current value of a source variable. If the variable is not
        in the cache it will be retrieved from the controller.