code: def physical_pins(self, function):
          
          return {
              (header, pin.number)
              for (header, info) in self.headers.items()
              for pin in info.pins.values()
              if pin.function == function
              }
docs: Return the physical pins supporting the specified *function* as tuples
          of ``(header, pin_number)`` where *header* is a string specifying the
          header containing the *pin_number*. Note that the return value is a
          :class:`set` which is not indexable. Use :func:`physical_pin` if you
          are expecting a single return value.
  
          :param str function:
              The pin function you wish to search for. Usually this is something
              like "GPIO9" for Broadcom GPIO pin 9, or "GND" for all the pins
              connecting to electrical ground.