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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def camel_case_to_under_score(camel_case_name):
 """Return the underscore name of a camel case name. :param str camel_case_name: a name in camel case such as ``"ACamelCaseName"`` :return: the name using underscores, e.g. ``"a_camel_case_name"`` :rtype: str """

    result = []
    for letter in camel_case_name:
        if letter.lower() != letter:
            result.append("_" + letter.lower())
        else:
            result.append(letter.lower())
    if result[0].startswith("_"):
        result[0] = result[0][1:]
    return "".join(result)