code: func (v *TextBuffer) GetIterAtMark(mark *TextMark) *TextIter {
  	var iter C.GtkTextIter
  	C.gtk_text_buffer_get_iter_at_mark(v.native(), &iter, (*C.GtkTextMark)(mark))
  	return (*TextIter)(&iter)
  }
docs: // GetIterAtMark() is a wrapper around gtk_text_buffer_get_iter_at_mark().