<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def register_master():
 """Register the SDP Master device."""

    tango_db = Database()
    device = "sip_sdp/elt/master"
    device_info = DbDevInfo()
    device_info._class = "SDPMasterDevice"
    device_info.server = "sdp_master_ds/1"
    device_info.name = device
    devices = tango_db.get_device_name(device_info.server, device_info._class)
    if device not in devices:
        LOG.info('Registering device "%s" with device server "%s"',
                 device_info.name, device_info.server)
        tango_db.add_device(device_info)