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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 parse_list(str_, sep=","):
 """ Simple parser to parse expressions reprensent some list values. :param str_: a string to parse :param sep: Char to separate items of list :return: [Int | Bool | String] [] [1] ['a', 'b'] [1, 2] ['a', 'b'] """

    return [parse_single(x) for x in str_.split(sep) if x]