python - SqlAchemy: Select coalesce columns -

i trying write equivalent of sql statement in sqlalchemy:

select coalesce(table1.column1, table2.column1), table1.column2 ... table1 full outer join table2 on table1.column1 = table2.column1 

when do

from sqlalchemy.sql.functions import coalesce sa.select([coalesce(...), <other columns>]).select_from(...) 

i error:

typeerror: boolean value of clause not defined