feat: add same_case function and tests

src/same_case.py

@@ -0,0 +1,10 @@
+# https://www.codewars.com/kata/5dd462a573ee6d0014ce715b
+
+def same_case(a, b):
+    if not a.isalpha() or not b.isalpha():
+        return -1
+
+    if (a.islower() and b.islower()) or (a.isupper() and b.isupper()):
+        return 1
+
+    return 0

tests/test_same_case.py

@@ -0,0 +1,8 @@
+from src.same_case import same_case
+
+def test_same_case():
+    assert same_case('a', 'g') == 1
+    assert same_case('A', 'C') == 1
+    assert same_case('b', 'G') == 0
+    assert same_case('B', 'g') == 0
+    assert same_case('0', '?') == -1