code: func (f *file) imports(importPath string) bool {
  	all := astutil.Imports(f.fset, f.f)
  	for _, p := range all {
  		for _, i := range p {
  			uq, err := strconv.Unquote(i.Path.Value)
  			if err == nil && importPath == uq {
  				return true
  			}
  		}
  	}
  	return false
  }
docs: // imports returns true if the current file imports the specified package path.