    def render_marker(self, counter_name, counter_value):
        """Generate the content of a ::marker pseudo-element."""
        counter = self.resolve_counter(counter_name)
        if counter is None:
            if 'decimal' in self:
                return self.render_marker('decimal', counter_value)
            else:
                # Could happen if the UA stylesheet is not used
                return ''

        prefix = symbol(counter['prefix'] or ('string', ''))
        suffix = symbol(counter['suffix'] or ('string', '. '))

        value = self.render_value(counter_value, counter_name=counter_name)
        assert value is not None
        return prefix + value + suffix
Generate the content of a ::marker pseudo-element.
weasyprint/css/counters.py