code: func (b *glusterfsMounter) CanMount() error {
  	exe := b.plugin.host.GetExec(b.plugin.GetPluginName())
  	switch runtime.GOOS {
  	case "linux":
  		if _, err := exe.Run("test", "-x", gciLinuxGlusterMountBinaryPath); err != nil {
  			return fmt.Errorf("Required binary %s is missing", gciLinuxGlusterMountBinaryPath)
  		}
  	}
  	return nil
  }
docs: // Checks prior to mount operations to verify that the required components (binaries, etc.)
  // to mount the volume are available on the underlying node.
  // If not, it returns an error