def get_process_flow(self, pid=None):
        '''
        get_process_flow(self, pid=None)

        Get process in flow context. The response returns a sub-tree of the whole flow containing the requested process, its direct children processes, and all ancestors.
        You can navigate within the flow backword and forward by running this call on the children or ancestors of a given process.

        :Parameters:
        * *pid* (`string`) -- Identifier of an existing process

        '''
        pid = self._get_pid(pid)
        return self._call_rest_api('get', '/processes/'+pid+'/flow', error='Failed to fetch process information')