Added improved models

src/cpl_reactive_extensions/abc/subscribable.py

@@ -0,0 +1,16 @@
+from abc import ABC, abstractmethod
+from typing import Union, Callable
+
+from cpl_reactive_extensions.abc.observer import Observer
+from cpl_reactive_extensions.abc.unsubscribable import Unsubscribable
+
+
+class Subscribable(ABC):
+    def __init__(self):
+        ABC.__init__(self)
+
+    @abstractmethod
+    def subscribe(
+        self, observer_or_next: Union[Callable, Observer], on_error: Callable = None, on_complete: Callable = None
+    ) -> Unsubscribable:
+        pass