diff --git a/jedi/evaluate/context/instance.py b/jedi/evaluate/context/instance.py
index ae1bb422..96b46b4f 100644
--- a/jedi/evaluate/context/instance.py
+++ b/jedi/evaluate/context/instance.py
@@ -146,8 +146,10 @@ class AbstractInstanceContext(Context):
     def py__getitem__(self, index_context_set, contextualized_node):
         names = self.get_function_slot_names(u'__getitem__')
         if not names:
-            debug.warning('Found no __getitem__ on %s', self)
-            return NO_CONTEXTS
+            return super(AbstractInstanceContext, self).py__getitem__(
+                index_context_set,
+                contextualized_node,
+            )
 
         args = ValuesArguments([index_context_set])
         return ContextSet.from_sets(name.infer().execute(args) for name in names)
diff --git a/jedi/evaluate/context/iterable.py b/jedi/evaluate/context/iterable.py
index 62da28b6..6ae64125 100644
--- a/jedi/evaluate/context/iterable.py
+++ b/jedi/evaluate/context/iterable.py
@@ -55,6 +55,12 @@ class GeneratorBase(LazyAttributeOverwrite, IterableMixin):
             .execute_annotation()
         return generator
 
+    def is_instance(self):
+        return False
+
+    def py__bool__(self):
+        return True
+
     @publish_method('__iter__')
     def py__iter__(self, contextualized_node=None):
         return ContextSet([self])
diff --git a/jedi/evaluate/syntax_tree.py b/jedi/evaluate/syntax_tree.py
index f65ad2e2..c8b9e45e 100644
--- a/jedi/evaluate/syntax_tree.py
+++ b/jedi/evaluate/syntax_tree.py
@@ -639,7 +639,7 @@ def _apply_decorators(context, node):
         decoratee_context = FunctionContext.from_context(context, node)
     initial = values = ContextSet([decoratee_context])
     for dec in reversed(node.get_decorators()):
-        debug.dbg('decorator: %s %s', dec, values)
+        debug.dbg('decorator: %s %s', dec, values, color="MAGENTA")
         with debug.increase_indent_cm():
             dec_values = context.eval_node(dec.children[1])
             trailer_nodes = dec.children[2:-1]
@@ -663,7 +663,7 @@ def _apply_decorators(context, node):
                 debug.warning('not possible to resolve wrappers found %s', node)
                 return initial
 
-        debug.dbg('decorator end %s', values)
+        debug.dbg('decorator end %s', values, color="MAGENTA")
     return values