Actually this code is required for processing ZAN library.
ZAN library has zql.erb file and user can write some queries there.
L class loads zql.erb and as you know, L extends Q and use method in Q to evaluate/execute zql.erb.

Later we need modify L to not use Q's method to evaluate/execute but use ZQL class to parse zql.erb.
until then, we can not use zql syntax inside of zql.erb.

That'll be large job, so better be handled in separate issue.