code: public static Closeable mountAssembly(VirtualFileAssembly assembly, VirtualFile mountPoint) throws IOException {
          return doMount(new AssemblyFileSystem(assembly), mountPoint);
      }
docs: Create and mount an assembly file system, returning a single handle which will unmount and
  close the filesystem when closed.
  
  @param assembly   an {@link VirtualFileAssembly} to mount in the VFS
  @param mountPoint the point at which the filesystem should be mounted
  @return a handle
  @throws IOException if an error occurs