type RWValue … func (v *RWValue) Set(value interface{ … } func (v *RWValue) Get() (interface{ … } // IsText reports whether a significant prefix of s looks like correct UTF-8; // that is, if it is likely that s is human-readable text. func IsText(s []byte) bool { … } var textExt … // IsTextFile reports whether the file has a known extension indicating // a text file, or if a significant chunk of the specified file looks like // correct UTF-8; that is, if it is likely that the file contains human- // readable text. func IsTextFile(fs vfs.Opener, filename string) bool { … }