How to use the haros.metamodel.SourceCondition function in haros

def _client_from_JSON(self, datum):
        l = self._location_from_JSON
        cs = [SourceCondition(c["condition"], location = l(c["location"]))
              for c in datum["conditions"]]
        return ServiceClientCall(datum["name"], datum["namespace"],
                                 datum["type"], control_depth = datum["depth"],
                                 repeats = datum["repeats"],
                                 conditions = cs,
                                 location = l(datum["location"]))

def _srv_from_JSON(self, datum):
        l = self._location_from_JSON
        cs = [SourceCondition(c["condition"], location = l(c["location"]))
              for c in datum["conditions"]]
        return ServiceServerCall(datum["name"], datum["namespace"],
                                 datum["type"], control_depth = datum["depth"],
                                 repeats = datum["repeats"],
                                 conditions = cs,
                                 location = l(datum["location"]))

def _on_subscription(self, node, ns, call, topic_pos=0, queue_pos=1,
                         msg_type=None):
        if len(call.arguments) <= 1:
            return
        name = self._extract_topic(call, topic_pos=topic_pos)
        msg_type = msg_type or self._extract_message_type(call)
        queue_size = self._extract_queue_size(call, queue_pos=queue_pos)
        depth = get_control_depth(call, recursive=True)
        location = self._call_location(call)
        conditions = [SourceCondition(pretty_str(c), location=location)
                      for c in get_conditions(call, recursive=True)]
        sub = Subscription(name, ns, msg_type, queue_size, location=location,
                           control_depth=depth, conditions=conditions,
                           repeats=is_under_loop(call, recursive=True))
        node.subscribe.append(sub)
        self.log.debug("Found Subscription on %s/%s (%s)", ns, name, msg_type)

def _condition(self, condition, sub, line, col):
        assert isinstance(condition, tuple)
        value = sub.resolve(condition[1], conversion=bool)
        if value is None:
            stmt = "if" if condition[0] else "unless"
            loc = self.configuration.roslaunch[-1].location
            loc.line = line
            loc.column = col
            # not sure if tag is part of the configuration
            return SourceCondition(condition[1], # UnresolvedValue
                location=loc, statement=stmt)
        if value is condition[0]:
            # tag is part of the configuration
            return True
        # tag is not part of the configuration
        return False

def _write_from_JSON(self, datum):
        l = self._location_from_JSON
        cs = [SourceCondition(c["condition"], location = l(c["location"]))
              for c in datum["conditions"]]
        return WriteParameterCall(datum["name"], datum["namespace"],
                                  datum["type"], control_depth = datum["depth"],
                                  repeats = datum["repeats"],
                                  conditions = cs,
                                  location = l(datum["location"]))

def _on_read_param(self, node, ns, call):
        if len(call.arguments) < 1:
            return
        name = self._extract_topic(call)
        depth = get_control_depth(call, recursive = True)
        location = self._call_location(call)
        conditions = [SourceCondition(pretty_str(c), location = location)
                      for c in get_conditions(call, recursive = True)]
        read = ReadParameterCall(name, ns, None, location = location,
                                 control_depth = depth, conditions = conditions,
                                 repeats = is_under_loop(call, recursive = True))
        node.read_param.append(read)
        self.log.debug("Found Read on %s/%s (%s)", ns, name, "string")

def _read_from_JSON(self, datum):
        l = self._location_from_JSON
        cs = [SourceCondition(c["condition"], location = l(c["location"]))
              for c in datum["conditions"]]
        return ReadParameterCall(datum["name"], datum["namespace"],
                                 datum["type"], control_depth = datum["depth"],
                                 repeats = datum["repeats"],
                                 conditions = cs,
                                 location = l(datum["location"]))