1 def execute(eyetracker):
     2     hmd_gaze_data(eyetracker)
     7 import tobii_research 
as tr
     9 global_hmd_gaze_data = 
None    12 def hmd_gaze_data_callback(hmd_gaze_data):
    13     global global_hmd_gaze_data
    14     global_hmd_gaze_data = hmd_gaze_data
    17 def hmd_gaze_data(eyetracker):
    18     global global_hmd_gaze_data
    20     print(
"Subscribing to gaze data for eye tracker with serial number {0}.".format(eyetracker.serial_number))
    21     eyetracker.subscribe_to(tr.EYETRACKER_HMD_GAZE_DATA, hmd_gaze_data_callback, as_dictionary=
True)
    26     eyetracker.unsubscribe_from(tr.EYETRACKER_HMD_GAZE_DATA, hmd_gaze_data_callback)
    27     print(
"Unsubscribed from HMD gaze data.")
    29     print(
"Last received HMD gaze package:")
    30     print(global_hmd_gaze_data)