camel.py

def main():
    user_input = input('camelCase: ') # removes every whitespace in between string
    print(camel_to_snake_case(user_input)) # camel_to_snake_case function call


def camel_to_snake_case(camelCaseString):
    # removes any space(s) in between with leading/trailing space(s) & "_"
    camelCaseString = camelCaseString.replace('_', '').strip(' ').replace(' ', '')

    if (any(char.isalpha() for char in camelCaseString)) and (any(char.isdigit() for char in camelCaseString)) :
        return camelCaseString
    else:
        for char in camelCaseString:
            if camelCaseString.__contains__(char.upper()):
                camelCaseString = camelCaseString.replace(char.upper(), f'_{char.lower()}')
                camelCaseString = camelCaseString.lstrip('_')
            else:
                camelCaseString
    return camelCaseString


if __name__ == '__main__':
    main()