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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 _get_server_certificate(addr, ssl_version=PROTOCOL_SSLv23, ca_certs=None):
 """Retrieve a server certificate Retrieve the certificate from the server at the specified address, and return it as a PEM-encoded string. If 'ca_certs' is specified, validate the server cert against it. If 'ssl_version' is specified, use it in the connection attempt. """


    if ssl_version not in (PROTOCOL_DTLS, PROTOCOL_DTLSv1, PROTOCOL_DTLSv1_2):
        return _orig_get_server_certificate(addr, ssl_version, ca_certs)

    if ca_certs is not None:
        cert_reqs = ssl.CERT_REQUIRED
    else:
        cert_reqs = ssl.CERT_NONE
    af = getaddrinfo(addr[0], addr[1])[0][0]
    s = ssl.wrap_socket(socket(af, SOCK_DGRAM),
                        ssl_version=ssl_version,
                        cert_reqs=cert_reqs, ca_certs=ca_certs)
    s.connect(addr)
    dercert = s.getpeercert(True)
    s.close()
    return ssl.DER_cert_to_PEM_cert(dercert)