Include ocmments about nesting

Python/026_matchnested.py

@@ -2,6 +2,11 @@
 # Note: Python's match implementation was introduced in Python version 3.10
 
 num = None
+# Note that this has a nested structure. There is an outer while loop
+# which contains an inner try/except block. Structures can be nested
+# at nearly infinite complexity, but if the structure gets more than
+# a short few nestings it gets confusing to read and functions
+# (dicussed later) should probably be used at that point.
 while num is None:
     try:
         num = int(input("Enter a number between 1 and 3: "))