diff --git a/urwid/main_loop.py b/urwid/main_loop.py
new file mode 100644
index 0000000..8333792
--- /dev/null
+++ b/urwid/main_loop.py
@@ -0,0 +1,98 @@
+import typing
+
+from urwid import signals
+from urwid.command_map import REDRAW_SCREEN, command_map
+# from urwid.compat import reraise # module removed, its code is copied below
+from urwid.display_common import INPUT_DESCRIPTORS_CHANGED
+from urwid.util import StoppingContext, is_mouse_event
+from urwid.wimp import PopUpTarget
+from urwid.event_loop import EventLoop, SelectEventLoop, AsyncioEventLoop
+from urwid.event_loop.main_loop import CantUseExternalLoop, ExitMainLoop, MainLoop
+try:
+    from urwid.event_loop.twisted_loop import FileDescriptor, TwistedEventLoop, _TwistedInputDescriptor as TwistedInputDescriptor
+except ImportError:
+    pass
+
+try:
+    from urwid.event_loop import TornadoEventLoop
+except ImportError:
+    pass
+
+try:
+    from urwid.event_loop import GLibEventLoop
+except ImportError:
+    pass
+
+try:
+    from urwid.event_loop import TrioEventLoop
+except ImportError:
+    pass
+
+if typing.TYPE_CHECKING:
+    from .display_common import BaseScreen
+    from .widget import Widget
+
+
+def reraise(tp, value, tb=None):
+    """
+    Reraise an exception.
+    Taken from "six" library (https://pythonhosted.org/six/).
+    """
+    try:
+        if value is None:
+            value = tp()
+        if value.__traceback__ is not tb:
+            raise value.with_traceback(tb)
+        raise value
+    finally:
+        value = None
+        tb = None
+
+
+def _refl(name: str, rval=None, exit=False):
+    """
+    This function is used to test the main loop classes.
+    >>> scr = _refl("screen")
+    >>> scr.function("argument")
+    screen.function('argument')
+    >>> scr.callme(when="now")
+    screen.callme(when='now')
+    >>> scr.want_something_rval = 42
+    >>> x = scr.want_something()
+    screen.want_something()
+    >>> x
+    42
+    """
+    class Reflect:
+        def __init__(self, name: int, rval=None):
+            self._name = name
+            self._rval = rval
+
+        def __call__(self, *argl, **argd):
+            args = ", ".join([repr(a) for a in argl])
+            if args and argd:
+                args = f"{args}, "
+            args = args + \
+                ", ".join([f"{k}={repr(v)}" for k, v in argd.items()])
+            print(f"{self._name}({args})")
+            if exit:
+                raise ExitMainLoop()
+            return self._rval
+
+        def __getattr__(self, attr):
+            if attr.endswith("_rval"):
+                raise AttributeError()
+            # print(self._name+"."+attr)
+            if hasattr(self, f"{attr}_rval"):
+                return Reflect(f"{self._name}.{attr}", getattr(self, f"{attr}_rval"))
+            return Reflect(f"{self._name}.{attr}")
+    return Reflect(name)
+
+
+def _test():
+    import doctest
+    doctest.testmod()
+
+
+if __name__ == '__main__':
+    _test()