code: func flagVolumeCapability(fs *flag.FlagSet, addr *volumeCapabilitySliceArg) {
  	fs.Var(
  		addr,
  		"cap",
  		`The volume capability is specified using the following format:
  `+flagVolumeCapabilityDescSuffix)
  }
docs: // flagVolumeCapability adds the --cap flag to the specified flagset.