complex sql no tables name

[lctlover]

ttt ="""

select * from ( (select a1,a2 from ta1 ) tt1 left join (select b1,b2 from tb1 ) tt2 on tt1.a1= tt2.b1) tt3

"""

Parser(ttt).columns ['*', 'a1', 'a2', 'b1', 'b2', 'tt1.a1']