added Notifier impl

treepuncher/notifier.py

@@ -0,0 +1,24 @@
+from typing import Callable, List
+
+class Notifier:
+	_report_functions : List[Callable]
+
+	def __init__(self):
+		self._report_functions = []
+
+	def register(self, fn:Callable):
+		self._report_functions.append(fn)
+		return fn
+
+	def report(self) -> str:
+		return '\n'.join(fn() for fn in self._report_functions)
+
+	def notify(self, text, **kwargs):
+		print(text)
+
+	async def initialize(self, _client:'Treepuncher'):
+		pass
+
+	async def cleanup(self, _client:'Treepuncher'):
+		pass
+