| call_nth/2 | True 
when Goal succeeded for the Nth time. | 
| distinct/1 | True 
if Goal is true and no previous solution of Goal bound Witness to the 
same value. | 
| distinct/2 | True 
if Goal is true and no previous solution of Goal bound Witness to the 
same value. | 
| group_by/4 | Group 
bindings of Template that have the same value for By. | 
| limit/2 | Limit 
the number of solutions. | 
| offset/2 | Ignore 
the first Count solutions. | 
| order_by/2 | Order 
solutions according to Spec. | 
| reduced/1 | Similar 
to distinct/1, but does not guarantee unique results in return for using 
a limited amount of memory. | 
| reduced/3 | Similar 
to distinct/1, but does not guarantee unique results in return for using 
a limited amount of memory. |