Simple case insensitive key matching for dictionaries

caseless_dict_search.py

def caseless_dict_search(dictionary, search_string):
    """ performs a case insensitive key search on a standard dictionary """
    # A dict matching lower case and actual case representations of the Keys
    keys_dict = {k.casefold(): k for k in dictionary.keys()}
    # Using the get() function to search dict with builtin error handling
    return dictionary.get(keys_dict.get(search_string.lower(), None), None)

test_dict = {"A": 0, "B": 1, "c": 2, "d":3}
INPUT = "D"  # Note case does not match any of the keys in the above dict
result = caseless_dict_search(test_dict, INPUT)
print(result)