#NEWLINE# def diffheaders( t1 , t2 ) : #NEWLINE# #INDENT# "\n    Return the difference between the headers of the two tables as a pair of\n    sets. E.g.::\n\n        >>> import petl as etl\n        >>> table1 = [['foo', 'bar', 'baz'],\n        ...           ['a', 1, .3]]\n        >>> table2 = [['baz', 'bar', 'quux'],\n        ...           ['a', 1, .3]]\n        >>> add, sub = etl.diffheaders(table1, table2)\n        >>> add\n        {'quux'}\n        >>> sub\n        {'foo'}\n\n    " #NEWLINE# t1h = set ( header ( t1 ) ) #NEWLINE# t2h = set ( header ( t2 ) ) #NEWLINE# return ( ( t2h - t1h ) , ( t1h - t2h ) )