Adopted new convention from template

src/Python/Problems001-050/Problem017.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 """
 Created on 13 Jan 2018
 
@@ -12,7 +12,7 @@ https://projecteuler.net/problem=17
 from utils import timeit
 
 
-def num2letters(num):
+def num_to_letters(num):
     nums = {
         0: "",
         1: "one",
@@ -50,18 +50,21 @@ def num2letters(num):
         return len(nums[num])
     elif num < 100:
         tens, units = divmod(num, 10)
-        return len(nums[tens * 10]) + num2letters(units)
+        return len(nums[tens * 10]) + num_to_letters(units)
     elif num < 1000:
         hundreds, rest = divmod(num, 100)
         if rest:
             return (
-                num2letters(hundreds) + len(nums[100]) + len("and") + num2letters(rest)
+                num_to_letters(hundreds)
+                + len(nums[100])
+                + len("and")
+                + num_to_letters(rest)
             )
         else:
-            return num2letters(hundreds) + len(nums[100])
+            return num_to_letters(hundreds) + len(nums[100])
     else:
-        thousands, rest = divmod(num, 1000)
-        return num2letters(thousands) + len(nums[1000])
+        thousands, _ = divmod(num, 1000)
+        return num_to_letters(thousands) + len(nums[1000])
 
 
 @timeit("Problem 17")
@@ -81,10 +84,9 @@ def compute():
     n = 1000
     letters = 0
     for num in range(1, n + 1):
-        letters += num2letters(num)
+        letters += num_to_letters(num)
     return letters
 
 
 if __name__ == "__main__":
-
-    print(f"Result for Problem 17: {compute()}")
+    print(f"Result for Problem 17 is {compute()}")