add nicer forward declaring type annotations

ezdag/layers.py

+from __future__ import annotations
+
 from collections.abc import Iterable
 from dataclasses import dataclass, field
 import itertools
@@ -133,7 +135,7 @@ class Layer:
             "retries": self.retries,
         }
 
-    def append(self, node: "Node"):
+    def append(self, node: Node):
         """Append a node to this layer."""
         assert isinstance(node.inputs, list)
         assert isinstance(node.outputs, list)
@@ -143,7 +145,7 @@ class Layer:
             self.outputs.setdefault(output.name, []).append(output.argument)
         self.nodes.append(node)
 
-    def extend(self, nodes: Iterable["Node"]):
+    def extend(self, nodes: Iterable[Node]):
         """Append multiple nodes to this layer."""
         for node in nodes:
             self.append(node)