Unfinished skeleton for Aggregate

eggstrain/src/execution/operators/aggregate.rs

@@ -0,0 +1,31 @@
+use super::{Operator, UnaryOperator};
+use async_trait::async_trait;
+
+/// TODO docs
+pub(crate) struct Aggregate {
+    children: Vec<Arc<dyn ExecutionPlan>>,
+}
+
+/// TODO docs
+impl Aggregate {
+    pub(crate) fn new() -> Self {
+        todo!();
+    }
+
+    fn aggregate_in_mem(&self, rb: RecordBatch) -> Result<RecordBatch> {
+        todo!();
+    }
+}
+
+/// TODO docs
+impl Operator for Aggregate {
+    fn children(&self) -> Vec<Arc<dyn ExecutionPlan>> {
+        todo!();
+    }
+}
+
+/// TODO docs
+#[async_trait]
+impl UnaryOperator for Aggregte {
+    todo!();
+}