def simple_function(input):
    """
    Adds a space every 3rd character of an input

    :param input: String - some string
    :returns: String - A string with a space between every 3rd character
    """
    output = ""
    for index in range(len(input)):
        if index%3==0 and index!=0:
            output += " "
        output += input[index]
    return output