chore: import upstream snapshot with attribution

scripts/check_installation.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+
+import easygraph as eg
+
+
+G = eg.Graph()
+
+G.add_edge(1, 2)
+assert G.edges == [(1, 2, {})]
+
+G.add_node("hello world")
+G.add_node("Jack", node_attr={"age": 10, "gender": "M"})
+assert G.nodes == {
+    1: {},
+    2: {},
+    "hello world": {},
+    "Jack": {"node_attr": {"age": 10, "gender": "M"}},
+}