'Initialize the ActivityInstance
:returns: twilio.rest.taskrouter.v1.workspace.activity.ActivityInstance
:rtype: twilio.rest.taskrouter.v1.workspace.activity.ActivityInstance'

def __init__(self, version, payload, workspace_sid, sid=None):

    super(ActivityInstance, self).__init__(version)
    self._properties = {'account_sid': payload['account_sid'], 'available': payload['available'], 'date_created': deserialize.iso8601_datetime(payload['date_created']), 'date_updated': deserialize.iso8601_datetime(payload['date_updated']), 'friendly_name': payload['friendly_name'], 'sid': payload['sid'], 'workspace_sid': payload['workspace_sid'], 'url': payload['url']}
    self._context = None
    self._solution = {'workspace_sid': workspace_sid, 'sid': (sid or self._properties['sid'])}
