Add stage base class, refactor discovery, etc
diff --git a/wally/ops_log.py b/wally/ops_log.py
new file mode 100644
index 0000000..48f2b61
--- /dev/null
+++ b/wally/ops_log.py
@@ -0,0 +1,9 @@
+from typing import Any
+
+
+log = []
+
+
+def log_op(name: str, *params: Any) -> None:
+    log.append([name] + list(params))
+