code: func resolveModeToString(rm source.ResolveMode) string {
  	switch rm {
  	case source.ResolveModeDefault:
  		return "default"
  	case source.ResolveModeForcePull:
  		return "pull"
  	case source.ResolveModePreferLocal:
  		return "local"
  	}
  	return ""
  }
docs: // resolveModeToString is the equivalent of github.com/moby/buildkit/solver/llb.ResolveMode.String()
  // FIXME: add String method on source.ResolveMode