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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 depth_walker(directory, maximum_depth=1):
 """ Defines a generator used to walk into directories using given maximum depth. Usage:: (u'./foundations/tests/tests_foundations/resources/standard/level_0', [u'level_1'], [u'standard.ibl']) (u'./foundations/tests/tests_foundations/resources/standard/level_0/level_1', [u'level_2'], [u'lorem_ipsum.txt', u'standard.rc']) (u'./foundations/tests/tests_foundations/resources/standard/level_0', [u'level_1'], [u'standard.ibl']) (u'./foundations/tests/tests_foundations/resources/standard/level_0/level_1', [u'level_2'], [u'lorem_ipsum.txt', u'standard.rc']) (u'./foundations/tests/tests_foundations/resources/standard/level_0/level_1/level_2', [], [u'standard.sIBLT']) :param directory: Directory to walk. :type directory: unicode :param maximum_depth: Maximum depth. :type maximum_depth: int :return: Parent directory, directories, files. :rtype: tuple """


    separator = os.path.sep
    base_depth = directory.count(separator)

    for parent_directory, directories, files in os.walk(directory):
        yield parent_directory, directories, files
        if base_depth + maximum_depth <= parent_directory.count(separator):
            del directories[:]