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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 from_rfc(datestring, use_dateutil=True):
 """Parse a RFC822-formatted datetime string and return a datetime object. Use dateutil's parser if possible. https://stackoverflow.com/questions/885015/how-to-parse-a-rfc-2822-date-time-into-a-python-datetime """

    # Use dateutil's parser if possible
    if dateutil_available and use_dateutil:
        return parser.parse(datestring)
    else:
        parsed = parsedate(datestring)  # as a tuple
        timestamp = time.mktime(parsed)
        return datetime.datetime.fromtimestamp(timestamp)