def _format_tree(self, node, total_samples):
        """Reformats call tree for the UI."""
        funcname, filename, _ = node['stack']
        sample_percent = self._get_percentage(
            node['sampleCount'], total_samples)
        color_hash = base_profiler.hash_name('%s @ %s' % (funcname, filename))
        return {
            'stack': node['stack'],
            'children': [self._format_tree(child, total_samples)
                         for child in node['children']],
            'sampleCount': node['sampleCount'],
            'samplePercentage': sample_percent,
            'colorHash': color_hash
        }
Reformats call tree for the UI.