Merge pull request #39 from SAK917/master

Replace assert with if statement (Fixes #32)

Author: ladyada

adafruit_mcp230xx/mcp23008.py

@@ -85,5 +85,6 @@ def get_pin(self, pin):
         """Convenience function to create an instance of the DigitalInOut class
         pointing at the specified pin of this MCP23008 device.
         """
-        assert 0 <= pin <= 7
+        if not 0 <= pin <= 7:
+            raise ValueError("Pin number must be 0-7.")
         return DigitalInOut(pin, self)

adafruit_mcp230xx/mcp23016.py

@@ -126,7 +126,8 @@ def get_pin(self, pin):
         """Convenience function to create an instance of the DigitalInOut class
         pointing at the specified pin of this MCP23016 device.
         """
-        assert 0 <= pin <= 15
+        if not 0 <= pin <= 15:
+            raise ValueError("Pin number must be 0-15.")
         return DigitalInOut(pin, self)
 
     def clear_inta(self):

adafruit_mcp230xx/mcp23017.py

@@ -163,7 +163,8 @@ def get_pin(self, pin):
         """Convenience function to create an instance of the DigitalInOut class
         pointing at the specified pin of this MCP23017 device.
         """
-        assert 0 <= pin <= 15
+        if not 0 <= pin <= 15:
+            raise ValueError("Pin number must be 0-15.")
         return DigitalInOut(pin, self)
 
     @property