NEW: itertools.len_permutations() and itertools.len_combinations() -> get the amount of results the respective itertools function would yield

src/tools/itertools.py

@@ -0,0 +1,20 @@
+from math import factorial
+from typing import Sized
+
+
+def len_combinations(iterable: Sized, r: int) -> int:
+    """How many options will itertools.combinations(iterable, r) yield?"""
+    n = len(iterable)
+    if r > n:
+        return 0
+    else:
+        return factorial(n) // factorial(r) // factorial(n - r)
+
+
+def len_permutations(iterable: Sized, r: int) -> int:
+    """How many options will itertools.permutations(iterable, r) yield?"""
+    n = len(iterable)
+    if r > n:
+        return 0
+    else:
+        return factorial(n) // factorial(n - r)