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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_timestamp(timestamp):
 """ Parse a given timestamp value, raising ValueError if None or Flasey """

        if timestamp:
            try:
                return aniso8601.parse_datetime(timestamp)
            except AttributeError:
                # raised by aniso8601 if raw_timestamp is not valid string
                # in ISO8601 format
                try:
                    return datetime.utcfromtimestamp(timestamp)
                except:
                    # relax the timestamp a bit in case it was sent in millis
                    return datetime.utcfromtimestamp(timestamp/1000)

        raise ValueError('Invalid timestamp value! Cannot parse from either ISO8601 string or UTC timestamp.')