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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 _domain_event_tray_change_cb(conn, domain, dev, reason, opaque):
    '''
    Domain tray change events handler
    '''
    _salt_send_domain_event(opaque, conn, domain, opaque['event'], {
        'dev': dev,
        'reason': _get_libvirt_enum_string('VIR_DOMAIN_EVENT_TRAY_CHANGE_', reason)
    })