fn plan_join(
left_qcx: &QueryContext<'_>,
left: HirRelationExpr,
left_scope: Scope,
join: &Join<Aug>
) -> Result<(HirRelationExpr, Scope), PlanError>
fn plan_join(
left_qcx: &QueryContext<'_>,
left: HirRelationExpr,
left_scope: Scope,
join: &Join<Aug>
) -> Result<(HirRelationExpr, Scope), PlanError>