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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 split(values, separator=re.compile("[ ,]+")):
 """ Convert space-or-comma-separated values into a single list Common use case for this is merging content of options with multiple values allowed into a single list of strings thus allowing any of the formats below and converts them into ['a', 'b', 'c']:: Accepts both string and list. By default space and comma are used as value separators. Use any regular expression for custom separator. """

    if not isinstance(values, list):
        values = [values]
    return sum([separator.split(value) for value in values], [])