def cancel_command(CommandId=None, InstanceIds=None):
    """
    Attempts to cancel the command specified by the Command ID. There is no guarantee that the command will be terminated and the underlying process stopped.
    See also: AWS API Documentation
    
    
    :example: response = client.cancel_command(
        CommandId='string',
        InstanceIds=[
            'string',
        ]
    )
    
    
    :type CommandId: string
    :param CommandId: [REQUIRED]
            The ID of the command you want to cancel.
            

    :type InstanceIds: list
    :param InstanceIds: (Optional) A list of instance IDs on which you want to cancel the command. If not provided, the command is canceled on every instance on which it was requested.
            (string) --
            

    :rtype: dict
    :return: {}
    
    
    """
    pass
