Add docstring.

Author: scoder

gen_todecimal.py

@@ -1,3 +1,6 @@
+"""
+Generate and print a C snippet that maps Unicode digit code points to ASCII digits.
+"""
 
 import sys
 import unicodedata
@@ -49,5 +52,6 @@ def gen_switch_cases(digits_by_adigit):
     print("        return -1;")
     print("}")
 
+
 if __name__ == '__main__':
     gen_switch_cases(map_to_ascii_digit(list_digits()))