How to use the react-native-webrtc.mediaDevices.getUserMedia function in react-native-webrtc

const facing = isFront ? 'front' : 'back';
    const videoSourceId = devices.find(device => device.kind === 'videoinput' && device.facing === facing);
    const facingMode = isFront ? 'user' : 'environment';
    const constraints = {
      audio: true,
      video: {
        mandatory: {
          minWidth: 500, // Provide your own width, height and frame rate here
          minHeight: 300,
          minFrameRate: 30,
        },
        facingMode,
        optional: videoSourceId ? [{sourceId: videoSourceId}] : [],
      },
    };
    const newStream = await mediaDevices.getUserMedia(constraints);
    setLocalStream(newStream);
  };

const _getUserMedia = (constraints: MediaStreamConstraints) => mediaDevices.getUserMedia(constraints)