[mypy] annotate `ciphers` (#5569)

* [mypy] annotate `ciphers`

* Update ciphers/polybius.py

* Update polybius.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

ciphers/decrypt_caesar_with_chi_squared.py

@@ -221,10 +221,13 @@ def decrypt_caesar_with_chi_squared(
 
     # Get the most likely cipher by finding the cipher with the smallest chi squared
     # statistic
-    most_likely_cipher: int = min(  # type: ignore
-        chi_squared_statistic_values,  # type: ignore
-        key=chi_squared_statistic_values.get,  # type: ignore
-    )  # type: ignore
+    def chi_squared_statistic_values_sorting_key(key: int) -> tuple[float, str]:
+        return chi_squared_statistic_values[key]
+
+    most_likely_cipher: int = min(
+        chi_squared_statistic_values,
+        key=chi_squared_statistic_values_sorting_key,
+    )
 
     # Get all the data from the most likely cipher (key, decoded message)
     (

ciphers/polybius.py

@@ -45,8 +45,7 @@ class PolybiusCipher:
         >>> PolybiusCipher().numbers_to_letter(1, 1) == "a"
         True
         """
-        letter = self.SQUARE[index1 - 1, index2 - 1]
-        return letter
+        return self.SQUARE[index1 - 1, index2 - 1]
 
     def encode(self, message: str) -> str:
         """