Added reverse_letters.py

strings/reverse_letters.py

@@ -0,0 +1,19 @@
+def reverse_letters(input_str: str) -> str:
+    """
+    Reverses letters in a given string without adjusting the position of the words
+    >>> reverse_letters('The cat in the hat')
+    'ehT tac ni eht tah'
+    >>> reverse_letters('The quick brown fox jumped over the lazy dog.')
+    'ehT kciuq nworb xof depmuj revo eht yzal .god'
+    >>> reverse_letters('Is this true?')
+    'sI siht ?eurt'
+    >>> reverse_letters("I   love       Python")
+    'I evol nohtyP'
+    """
+    return " ".join([word[::-1] for word in input_str.split()])
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()