- redefine activate method

- for task introduced open() conext method

components/aplant.py

@@ -1,15 +1,30 @@
 import abc
 from utils.value import AttributeChange
+from contextlib import contextmanager
 
 
 class APlant(AttributeChange):
 	def __init__(self):
 		AttributeChange.__init__(self)
 
+	@contextmanager
+	def open(self):
+		try:
+			self.activate(True)
+			yield None
+		finally:
+			self.activate(False)
+
+		return None
+
 	@abc.abstractmethod
 	def activate(self, enable):
 		return None
 
+	@abc.abstractmethod
+	def is_activated(self):
+		return None
+
 	@abc.abstractmethod
 	def process(self):
 		pass