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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 _metric_unit_from_name(metric_name):
 """ Return a metric unit string for human consumption, that is inferred from the metric name. If a unit cannot be inferred, `None` is returned. """

    for item in _PATTERN_UNIT_LIST:
        pattern, unit = item
        if pattern.match(metric_name):
            return unit
    return None