Merge pull request #35 from adafruit/tannewt-patch-1

Use a tuple so that POSITIONS can be long lived.

Author: makermelissa

adafruit_ht16k33/segments.py

@@ -215,7 +215,7 @@ def _number(self, number):
 class Seg7x4(Seg14x4):
     """Numeric 7-segment display. It has the same methods as the alphanumeric display, but only
        supports displaying a limited set of characters."""
-    POSITIONS = [0, 2, 6, 8] #  The positions of characters.
+    POSITIONS = (0, 2, 6, 8) #  The positions of characters.
 
     def scroll(self, count=1):
         """Scroll the display by specified number of places."""