How to use the dsub.providers.google_base.parse_rfc3339_utc_string function in dsub

if self._job_descriptor:
        items = providers_util.get_job_and_task_param(
            self._job_descriptor.job_params,
            self._job_descriptor.task_descriptors[0].task_params, field)
        value = {item.name: item.value for item in items}
    elif field == 'create-time':
      ds = google_v2_operations.get_create_time(self._op)
      value = google_base.parse_rfc3339_utc_string(ds)
    elif field == 'start-time':
      ds = google_v2_operations.get_start_time(self._op)
      if ds:
        value = google_base.parse_rfc3339_utc_string(ds)
    elif field == 'end-time':
      ds = google_v2_operations.get_end_time(self._op)
      if ds:
        value = google_base.parse_rfc3339_utc_string(ds)
    elif field == 'status':
      value = self._operation_status()
    elif field == 'status-message':
      msg, action = self._operation_status_message()
      if msg.startswith('Execution failed:'):
        # msg may look something like
        # "Execution failed: action 2: pulling image..."
        # Emit the actual message ("pulling image...")
        msg = msg.split(': ', 2)[-1]
      value = msg
    elif field == 'status-detail':
      msg, action = self._operation_status_message()
      if action:
        value = action.get('name') + ':\n' + msg
      else:
        value = msg

if msg.startswith('Execution failed:'):
        # msg may look something like
        # "Execution failed: action 2: pulling image..."
        # Emit the actual message ("pulling image...")
        msg = msg.split(': ', 2)[-1]
      value = msg
    elif field == 'status-detail':
      msg, action = self._operation_status_message()
      if action:
        value = action.get('name') + ':\n' + msg
      else:
        value = msg
    elif field == 'last-update':
      last_update = google_v2_operations.get_last_update(self._op)
      if last_update:
        value = google_base.parse_rfc3339_utc_string(last_update)
    elif field == 'provider':
      return _PROVIDER_NAME
    elif field == 'provider-attributes':
      value = {}

      # The VM instance name and zone can be found in the WorkerAssignedEvent.
      # For a given operation, this may have occurred multiple times, so be
      # sure to grab the most recent.
      assigned_events = google_v2_operations.get_worker_assigned_events(
          self._op)
      if assigned_events:
        details = assigned_events[0].get('details', {})
        value['instance-name'] = details.get('instance')
        value['zone'] = details.get('zone')

      # The rest of the information comes from the request itself.

elif field == 'mounts':
      value = None
    elif field == 'create-time':
      value = google_base.parse_rfc3339_utc_string(metadata['createTime'])
    elif field == 'start-time':
      # Look through the events list for all "start" events (only one expected).
      start_events = [
          e for e in metadata.get('events', []) if e['description'] == 'start'
      ]
      # Get the startTime from the last "start" event.
      if start_events:
        value = google_base.parse_rfc3339_utc_string(
            start_events[-1]['startTime'])
    elif field == 'end-time':
      if 'endTime' in metadata:
        value = google_base.parse_rfc3339_utc_string(metadata['endTime'])
    elif field == 'status':
      value = self._operation_status()
    elif field in ['status-message', 'status-detail']:
      status, last_update = self._operation_status_message()
      value = status
    elif field == 'last-update':
      status, last_update = self._operation_status_message()
      value = last_update
    elif field == 'provider':
      return _PROVIDER_NAME
    elif field == 'provider-attributes':
      # Use soft getting of keys to address a race condition and to
      # pull the null values found in jobs that fail prior to scheduling.
      gce_data = metadata.get('runtimeMetadata', {}).get('computeEngine', {})
      if 'machineType' in gce_data:
        machine_type = gce_data.get('machineType').rpartition('/')[2]

]:
      if self._job_descriptor:
        value = {}
        items = providers_util.get_job_and_task_param(
            self._job_descriptor.job_params,
            self._job_descriptor.task_descriptors[0].task_params, field)
        value.update({item.name: item.value for item in items})
    elif field == 'mounts':
      if self._job_descriptor:
        items = providers_util.get_job_and_task_param(
            self._job_descriptor.job_params,
            self._job_descriptor.task_descriptors[0].task_params, field)
        value = {item.name: item.value for item in items}
    elif field == 'create-time':
      ds = google_v2_operations.get_create_time(self._op)
      value = google_base.parse_rfc3339_utc_string(ds)
    elif field == 'start-time':
      ds = google_v2_operations.get_start_time(self._op)
      if ds:
        value = google_base.parse_rfc3339_utc_string(ds)
    elif field == 'end-time':
      ds = google_v2_operations.get_end_time(self._op)
      if ds:
        value = google_base.parse_rfc3339_utc_string(ds)
    elif field == 'status':
      value = self._operation_status()
    elif field == 'status-message':
      msg, action = self._operation_status_message()
      if msg.startswith('Execution failed:'):
        # msg may look something like
        # "Execution failed: action 2: pulling image..."
        # Emit the actual message ("pulling image...")

def _map(self, event):
    """Extract elements from an operation event and map to a named event."""
    description = event.get('description', '')
    start_time = google_base.parse_rfc3339_utc_string(
        event.get('timestamp', ''))

    for name, regex in _EVENT_REGEX_MAP.items():
      match = regex.match(description)
      if match:
        return {'name': name, 'start-time': start_time}, match

    return {'name': description, 'start-time': start_time}, None