def _getPageInfo(self, pno, what):
        """Show fonts or images used on a page."""
        if self.isClosed or self.isEncrypted:
            raise ValueError("operation illegal for closed / encrypted doc")

        val = _fitz.Document__getPageInfo(self, pno, what)

        x = []
        for v in val:
            if v not in x:
                x.append(v)
        val = x

        return val
Show fonts or images used on a page.