primeiro commit com exercicios de Exercism realizados até esta data

python/rotational-cipher/rotational_cipher.py

@@ -0,0 +1,19 @@
+def rotate(text, key):
+    cyphertext: str = ""
+    for letter in text:
+        if letter.isalpha():
+            # check if letter is uppercase or lower case,
+            # and set add_value accordingly
+            if ord(letter) >= ord("A") and ord(letter) <= ord("Z"):
+                add_value = ord("A")
+            else:
+                add_value = ord("a")
+            # mod_value
+            mod_value = add_value + 26
+            cyphertext += chr(
+                ((ord(letter) + key) % mod_value)
+                + (((ord(letter) + key) // mod_value) * add_value)
+            )
+        else:
+            cyphertext += letter
+    return cyphertext