Method implement

src/plan/project.rs:49–75

(
        &self,
        nested: &mut Iterative<'b, S, u64>,
        local_arrangements: &VariableMap<Iterative<'b, S, u64>>,
        context: &mut I,
    )

    }

    fn implement<'b, T, I, S>(
        &self,
        nested: &mut Iterative<'b, S, u64>,
        local_arrangements: &VariableMap<Iterative<'b, S, u64>>,
        context: &mut I,
    ) -> (Implemented<'b, S>, ShutdownHandle)
    where
        T: Timestamp + Lattice,
        I: ImplContext<T>,
        S: Scope<Timestamp = T>,
    {
        let (relation, mut shutdown_handle) =
            self.plan.implement(nested, local_arrangements, context);
        let tuples = {
            let (projected, shutdown) = relation.projected(nested, context, &self.variables);
            shutdown_handle.merge_with(shutdown);

            projected
        };

        let projected = CollectionRelation {
            variables: self.variables.to_vec(),
            tuples,
        };

        (Implemented::Collection(projected), shutdown_handle)
    }
}