def start_on_demand_replication_run(replicationJobId=None, description=None):
    """
    The StartOnDemandReplicationRun API is used to start a ReplicationRun on demand (in addition to those that are scheduled based on your frequency). This ReplicationRun will start immediately. StartOnDemandReplicationRun is subject to limits on how many on demand ReplicationRuns you may call per 24-hour period.
    See also: AWS API Documentation
    
    
    :example: response = client.start_on_demand_replication_run(
        replicationJobId='string',
        description='string'
    )
    
    
    :type replicationJobId: string
    :param replicationJobId: [REQUIRED] The unique identifier for a Replication Job.

    :type description: string
    :param description: The description for a Replication Job/Run.

    :rtype: dict
    :return: {
        'replicationRunId': 'string'
    }
    
    
    :returns: 
    (dict) --
    replicationRunId (string) -- The unique identifier for a Replication Run.
    
    
    
    """
    pass
