How to use the datetime.datetime.utcfromtimestamp function in DateTime

def atest_root(kernel32_idb):
    root = idb.netnode.get_nodeid(kernel32_idb, 'Root Node')
    assert idb.netnode.get_int(kernel32_idb, root, 'A', idb.netnode.ROOT_INDEX.VERSION) == 695
    assert idb.netnode.get_string(kernel32_idb, root, 'S', idb.netnode.ROOT_INDEX.VERSION_STRING) == '6.95'
    assert idb.netnode.get_int(kernel32_idb, root, 'A', idb.netnode.ROOT_INDEX.OPEN_COUNT) == 1
    ts = idb.netnode.get_int(kernel32_idb, root, 'A', idb.netnode.ROOT_INDEX.CREATED)
    ts = datetime.datetime.utcfromtimestamp(ts)
    assert ts.isoformat() == '2017-06-20T22:31:34'
    assert idb.netnode.get_int(kernel32_idb, root, 'A', idb.netnode.ROOT_INDEX.CRC) == 0xdf9bdf12
    md5 = idb.netnode.get_bytes(kernel32_idb, root, 'S', idb.netnode.ROOT_INDEX.MD5)
    md5 = binascii.hexlify(md5).decode('ascii')
    assert md5 == '00bf1bf1b779ce1af41371426821e0c2'

def epochToString(D):
    return datetime.datetime.utcfromtimestamp(D).strftime(
        "%Y-%m-%d %H:%M:%S"
    )

def _serialize(self, value, attr, obj, **kwargs):
        """
        Serialize value as a timestamp, either as a Unix timestamp (in float second) or a UTC isoformat string.

        """
        if value is None:
            return None

        if self.use_isoformat:
            return datetime.utcfromtimestamp(value).isoformat()
        else:
            return value

def get_commit_time(self):
        return datetime.utcfromtimestamp(int(self.package.repo.commit_to_time(
            self.specified_revision)))

def get_target_start_date(self) -> Optional[datetime]:
        return datetime.utcfromtimestamp(cast(int, self.get_state("target_start_date")))

# section a
                elif format_version == 23:
                    latest_exec_date = content[0x0080:0x0080 + 8]
                    exec_count = struct.unpack("

def populate_result(self):
        substrate = self.decoded_response
        try:
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['partition_id'] = int(decoded)
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['replica_state'] = int(decoded)
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['modification_time'] = datetime.utcfromtimestamp(int(decoded))
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['purge_time'] = datetime.utcfromtimestamp(int(decoded))
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['local_partition_id'] = int(decoded)
            decoded, substrate = decoder.decode(substrate, asn1Spec=LDAPDN())
            self.result['partition_dn'] = str(decoded)
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['replica_type'] = int(decoded)
            decoded, substrate = decoder.decode(substrate, asn1Spec=Integer())
            self.result['flags'] = int(decoded)
        except Exception:
            raise LDAPExtensionError('unable to decode substrate')

        if substrate:
            raise LDAPExtensionError('unknown substrate remaining')

headers.append((x_header_name, safe_str(x_filename)))
        return Response('', status=200, headers=headers,
            direct_passthrough=True)
    else:
        request = environ.get('werkzeug.request')
        if request:
            range = request.range
        else:
            range = parse_range_header(environ.get('HTTP_RANGE'))
        #when request range,only recognize "bytes" as range units
        if range and range.units=="bytes":
            try:
                fsize = os.path.getsize(real_filename)
            except OSError as e:
                return Response("Not found",status=404)
            mtime = datetime.utcfromtimestamp(os.path.getmtime(real_filename))
            mtime_str = http_date(mtime)
            if cache:
                etag = _generate_etag(mtime, fsize, real_filename)
            else:
                etag = mtime_str

            if_range = environ.get('HTTP_IF_RANGE')
            if if_range:
                check_if_range_ok = (if_range.strip('"')==etag)
                #print "check_if_range_ok (%s) = (%s ==%s)"%(check_if_range_ok,if_range.strip('"'),etag)
            else:
                check_if_range_ok = True

            rbegin,rend = range.ranges[0]
            if check_if_range_ok and (rbegin+1)

def utc_milliseconds(timestamp=None):
  if timestamp is None: timestamp = datetime.utcnow()
  epoch = datetime.utcfromtimestamp(0)
  return long((timestamp - epoch).total_seconds() * 1000)

def get_readable_time():
    ts = int(time.time())
    return str(datetime.utcfromtimestamp(ts).strftime('%Y.%m.%d')) + f"__{ts}"