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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def server_reboot(host=None,
                  admin_username=None,
                  admin_password=None,
                  module=None):
    '''
    Issues a power-cycle operation on the managed server. This action is
    similar to pressing the power button on the system's front panel to
    power down and then power up the system.

    host
        The chassis host.

    admin_username
        The username used to access the chassis.

    admin_password
        The password used to access the chassis.

    module
        The element to reboot on the chassis such as a blade. If not provided,
        the chassis will be rebooted.

    CLI Example:

    .. code-block:: bash

        salt dell dracr.server_reboot
        salt dell dracr.server_reboot module=server-1

    '''
    return __execute_cmd('serveraction powercycle',
                         host=host, admin_username=admin_username,
                         admin_password=admin_password, module=module)