<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def planner(self, *, resource=''):
 """ Get an instance to read information from Microsoft planner """


        if not isinstance(self.protocol, MSGraphProtocol):
            # TODO: Custom protocol accessing OneDrive/Sharepoint Api fails here
            raise RuntimeError(
                'planner api only works on Microsoft Graph API')

        return Planner(parent=self, main_resource=resource)