How to use the itk/extensionToMeshIO.has function in itk

return PromiseFileReader.readAsArrayBuffer(file)
            .then(fileContents => {
              const vtiReader = vtkXMLImageDataReader.newInstance()
              vtiReader.parseAsArrayBuffer(fileContents)
              return Promise.resolve({ is3D: true, data: vtiReader.getOutputData(0)})
            })
        }
        else if(extensionToPolyDataIO.has(extension)) {
          return readPolyDataFile(null, file).then(({ polyData, webWorker }) => {
            webWorker.terminate()
            const is3D = true
            return Promise.resolve({ is3D, data: vtk(polyData) })
          }).catch((error) => {
            reject(error)
          })
        } else if(extensionToMeshIO.has(extension)) {
          let is3D = true
          const read0 = performance.now()
          let convert0 = null
          return readMeshFile(null, file).then(({ mesh: itkMesh, webWorker }) => {
            const read1 = performance.now();
            const duration = Number(read1 - read0).toFixed(1).toString()
            console.log("Mesh reading took " + duration + " milliseconds.")
            webWorker.terminate()
            const pipelinePath = 'MeshToPolyData'
            const args = ['mesh.json', 'polyData.json']
            const desiredOutputs = [
              { path: args[1], type: IOTypes.vtkPolyData }
            ]
            const inputs = [
              { path: args[0], type: IOTypes.Mesh, data: itkMesh }
            ]