remove common whitespace prefix from lines
    :param value:
    :return:

def outdent(value):
    """
    remove common whitespace prefix from lines
    :param value:
    :return:
    """
    try:
        num = 100
        lines = toString(value).splitlines()
        for l in lines:
            trim = len(l.lstrip())
            if trim > 0:
                num = min(num, len(l) - len(l.lstrip()))
        return CR.join([l[num:] for l in lines])
    except Exception as e:
        if not _Log:
            _late_import()

        _Log.error("can not outdent value", e)