code: func OpenFile(name string, flag int, perm os.FileMode) (*ZipArchive, error) {
  	z := new(ZipArchive)
  	err := z.Open(name, flag, perm)
  	return z, err
  }
docs: // OpenFile is the generalized open call; most users will use Open
  // instead. It opens the named zip file with specified flag
  // (O_RDONLY etc.) if applicable. If successful,
  // methods on the returned ZipArchive can be used for I/O.
  // If there is an error, it will be of type *PathError.