collectives: all_gather
        Gather the values from all processes. all_reduce Combine the results from
        all processes. all_to_all Every process sends data to every other process.
        broadcast Broadcast data from one process to all other processes. gather
        Gather the values from all processes to the root. reduce Combine the results
        from all processes to the root. scan Prefix reduction of the values from
        all processes. scatter Scatter the values stored at the root to all 