Added comment.

Author: StevenBruinen

adafruit_tca9548a.py

@@ -83,6 +83,7 @@ def writeto(self, address, buffer, **kwargs):
 
     def writeto_then_readfrom(self, address, buffer_out, buffer_in, **kwargs):
         """Pass thru for writeto_then_readfrom."""
+        """In linux, at least, this is a special kernel function call"""
         if address == self.tca.address:
             raise ValueError("Device address must be different than TCA9548A address.")
         return self.tca.i2c.writeto_then_readfrom(address, buffer_out, buffer_in, **kwargs)