code: func (i *ImportRestriction) ForbiddenImportsFor(pkg Package) ([]string, error) {
  	if restricted, err := i.isRestrictedDir(pkg.Dir); err != nil {
  		return []string{}, err
  	} else if !restricted {
  		return []string{}, nil
  	}
  
  	return i.forbiddenImportsFor(pkg), nil
  }
docs: // ForbiddenImportsFor determines all of the forbidden
  // imports for a package given the import restrictions