/// check to see if this e-node corresponds to a term that is grounded by
/// the variables bound at this point
check to see if this e-node corresponds to a term that is grounded by
the variables bound at this point
check to see if this e - node corresponds to a term that is grounded by the variables bound at this point
fn is_ground_now(&self, id: Id) -> bool {
        self.free_vars[usize::from(id)]
            .iter()
            .all(|v| self.v2r.contains_key(v))
    }
fn is_ground_now ( & self , id : Id ) -> bool { self . free_vars [ usize :: from ( id ) ] . iter ( ) . all ( | v | self . v2r . contains_key ( v ) ) }
check to see if this e-node corresponds to a term that is grounded by
the variables bound at this point
check to see if this e - node corresponds to a term that is grounded by the variables bound at this point
&self
id
Id