Raspberry Pi / Python Bluetooth Interface to Heart Rate Monitor

We have an existing application written for the Raspberry Pi using Python. The GUI is full screen using Tkinter. We wish to add to to our program a display of a users heart rate using a bluetooth heart rate monitor. Currently we use a Polar, Zephyr and Garmin but we would like to use as many different models as possible. The completed project will involve a series of functions written in Python. Function 1 (to be called init_bluetooth) will initialise the bluetooth interface for use. Function 2 (to be called scan_bluetooth) will scan for available bluetooth devices for a fixed number of second and return a list of available devices. Function 3 (to be called connect_bluetooth(deviceid)) will accept the name/id of a bluetooth device as its parameter and connect to the device. Function 4 (to be called gethr_bluetooth) will query the bluetooth device and get the current heart rate reading. No interface is necessary. You will deliver the above 4 functions and any additional code as needed to demonstrate the program working in a terminal window running python from command line.