def _check_proc_tree_schema(data):
    """Return true if expected process tree columns are present."""
    input_cols = set(data.columns)
    expected_cols = set(['new_process_lc', 'parent_proc_lc', 'source_index',
        'new_process_lc_par', 'source_index_par', 'parent_key', 'IsRoot',
        'IsLeaf', 'IsBranch', 'path', 'parent_index'])
    return expected_cols - input_cols
