def CheckPrev(callsignKey, dataKey, value):
            print "CheckPrev if callsign in nprev_vals: ", callsignKey, " key: ", dataKey, " Value: ", value 
            if nprev_vals.has_key(callsignKey) == 1:
                print "nprev_vals already has entry: ", callsignKey
            else:
                print "nprev_vals doesn't exist for callsignKey: ", callsignKey
                nprev_vals[callsignKey] = {}
                nprev_vals[callsignKey] = {'latitude': 0, 'longitude': 0, "altitude": 0, "speed": 0, 'maxA': 0}
                nprev_vals[callsignKey][dataKey] = value
                print "nprev_vals for callsignKey: ", callsignKey, " is: ", nprev_vals[callsignKey]