How to use the sdp.getMid function in sdp

sections.forEach(function(mediaSection, sdpMLineIndex) {
      var lines = SDPUtils.splitLines(mediaSection);
      var kind = SDPUtils.getKind(mediaSection);
      var rejected = SDPUtils.isRejected(mediaSection);
      var protocol = lines[0].substr(2).split(' ')[2];

      var direction = SDPUtils.getDirection(mediaSection, sessionpart);
      var remoteMsid = SDPUtils.parseMsid(mediaSection);

      var mid = SDPUtils.getMid(mediaSection) || SDPUtils.generateIdentifier();

      // Reject datachannels which are not implemented yet.
      if (kind === 'application' && protocol === 'DTLS/SCTP') {
        self.transceivers[sdpMLineIndex] = {
          mid: mid,
          isDatachannel: true
        };
        return;
      }

      var transceiver;
      var iceGatherer;
      var iceTransport;
      var dtlsTransport;
      var rtpReceiver;
      var sendEncodingParameters;

sections.forEach(function(mediaSection, sdpMLineIndex) {
      var lines = SDPUtils.splitLines(mediaSection);
      var kind = SDPUtils.getKind(mediaSection);
      var rejected = SDPUtils.isRejected(mediaSection);
      var protocol = lines[0].substr(2).split(' ')[2];

      var direction = SDPUtils.getDirection(mediaSection, sessionpart);
      var remoteMsid = SDPUtils.parseMsid(mediaSection);

      var mid = SDPUtils.getMid(mediaSection) || SDPUtils.generateIdentifier();

      // Reject datachannels which are not implemented yet.
      if (kind === 'application' && protocol === 'DTLS/SCTP') {
        self.transceivers[sdpMLineIndex] = {
          mid: mid,
          isDatachannel: true
        };
        return;
      }

      var transceiver;
      var iceGatherer;
      var iceTransport;
      var dtlsTransport;
      var rtpReceiver;
      var sendEncodingParameters;

sections.forEach(function(mediaSection, sdpMLineIndex) {
      var lines = SDPUtils.splitLines(mediaSection);
      var kind = SDPUtils.getKind(mediaSection);
      var rejected = SDPUtils.isRejected(mediaSection);
      var protocol = lines[0].substr(2).split(' ')[2];

      var direction = SDPUtils.getDirection(mediaSection, sessionpart);
      var remoteMsid = SDPUtils.parseMsid(mediaSection);

      var mid = SDPUtils.getMid(mediaSection) || SDPUtils.generateIdentifier();

      // Reject datachannels which are not implemented yet.
      if (kind === 'application' && protocol === 'DTLS/SCTP') {
        self.transceivers[sdpMLineIndex] = {
          mid: mid,
          isDatachannel: true
        };
        return;
      }

      var transceiver;
      var iceGatherer;
      var iceTransport;
      var dtlsTransport;
      var rtpReceiver;
      var sendEncodingParameters;

sections.forEach(function(mediaSection, sdpMLineIndex) {
      var lines = SDPUtils.splitLines(mediaSection);
      var kind = SDPUtils.getKind(mediaSection);
      var rejected = SDPUtils.isRejected(mediaSection);
      var protocol = lines[0].substr(2).split(' ')[2];

      var direction = SDPUtils.getDirection(mediaSection, sessionpart);
      var remoteMsid = SDPUtils.parseMsid(mediaSection);

      var mid = SDPUtils.getMid(mediaSection) || SDPUtils.generateIdentifier();

      // Reject datachannels which are not implemented yet.
      if (kind === 'application' && protocol === 'DTLS/SCTP') {
        self.transceivers[sdpMLineIndex] = {
          mid: mid,
          isDatachannel: true
        };
        return;
      }

      var transceiver;
      var iceGatherer;
      var iceTransport;
      var dtlsTransport;
      var rtpReceiver;
      var sendEncodingParameters;

const results = ((content.transport! as JingleIce).candidates || []).map(async json => {
                const candidate = SDPUtils.writeCandidate(convertCandidateToIntermediate(json));

                let sdpMLineIndex!: number;
                // workaround for https://bugzilla.mozilla.org/show_bug.cgi?id=1456417
                const remoteSDP = this.pc.remoteDescription!.sdp;
                const mediaSections = SDPUtils.getMediaSections(remoteSDP);
                for (let i = 0; i < mediaSections.length; i++) {
                    if (SDPUtils.getMid(mediaSections[i]) === sdpMid) {
                        sdpMLineIndex = i;
                        break;
                    }
                }

                if (this.pc.signalingState === 'stable') {
                    try {
                        await this.pc.addIceCandidate({ sdpMid, sdpMLineIndex, candidate });
                    } catch (err) {
                        this._log('error', 'Could not add ICE candidate', err);
                    }
                } else {
                    this.candidateBuffer.push({ sdpMid, sdpMLineIndex, candidate });
                }
            });
            return Promise.all(results);

const semantics = parts.shift()!.substr(8);
        session.groups.push({
            mids: parts,
            semantics
        });
    }

    for (const mediaSection of mediaSections) {
        const kind = SDP.getKind(mediaSection);
        const isRejected = SDP.isRejected(mediaSection);
        const mLine = SDP.parseMLine(mediaSection);

        const media: IntermediateMediaDescription = {
            direction: SDP.getDirection(mediaSection, sessionPart),
            kind,
            mid: SDP.getMid(mediaSection),
            protocol: mLine.protocol
            // TODO: what about end-of-candidates?
        };

        if (!isRejected) {
            media.iceParameters = SDP.getIceParameters(mediaSection, sessionPart);
            media.dtlsParameters = SDP.getDtlsParameters(mediaSection, sessionPart);
            media.setup = SDP.matchPrefix(mediaSection, 'a=setup:')[0].substr(8);
        }

        if (kind === 'audio' || kind === 'video') {
            media.rtpParameters = SDP.parseRtpParameters(mediaSection);
            media.rtpEncodingParameters = SDP.parseRtpEncodingParameters(mediaSection);
            media.rtcpParameters = SDP.parseRtcpParameters(mediaSection);
            const msid = SDP.parseMsid(mediaSection);
            media.streams = msid ? [msid] : [];