diff --git a/Lib/lib2to3/btm_utils.py b/Lib/lib2to3/btm_utils.py
--- a/Lib/lib2to3/btm_utils.py
+++ b/Lib/lib2to3/btm_utils.py
@@ -91,18 +91,17 @@ class MinNode(object):
         for l in self.leaves():
             subp = l.leaf_to_root()
             if subp:
                 return subp
 
     def leaves(self):
         "Generator that returns the leaves of the tree"
         for child in self.children:
-            for x in child.leaves():
-                yield x
+            yield from child.leaves()
         if not self.children:
             yield self
 
 def reduce_tree(node, parent=None):
     """
     Internal function. Reduces a compiled pattern tree to an
     intermediate representation suitable for feeding the
     automaton. This also trims off any optional pattern elements(like
@@ -272,12 +271,11 @@ def get_characteristic_subpattern(subpat
     # of the remaining subpatterns pick out the longest one
     return max(subpatterns, key=len)
 
 def rec_test(sequence, test_func):
     """Tests test_func on all items of sequence and items of included
     sub-iterables"""
     for x in sequence:
         if isinstance(x, (list, tuple)):
-            for y in rec_test(x, test_func):
-                yield y
+            yield from rec_test(x, test_func)
         else:
             yield test_func(x)
diff --git a/Lib/lib2to3/pytree.py b/Lib/lib2to3/pytree.py
--- a/Lib/lib2to3/pytree.py
+++ b/Lib/lib2to3/pytree.py
@@ -189,18 +189,17 @@ class Base(object):
         for i, child in enumerate(self.parent.children):
             if child is self:
                 if i == 0:
                     return None
                 return self.parent.children[i-1]
 
     def leaves(self):
         for child in self.children:
-            for x in child.leaves():
-                yield x
+            yield from child.leaves()
 
     def depth(self):
         if self.parent is None:
             return 0
         return 1 + self.parent.depth()
 
     def get_suffix(self):
         """
@@ -269,26 +268,24 @@ class Node(Base):
     def clone(self):
         """Return a cloned (deep) copy of self."""
         return Node(self.type, [ch.clone() for ch in self.children],
                     fixers_applied=self.fixers_applied)
 
     def post_order(self):
         """Return a post-order iterator for the tree."""
         for child in self.children:
-            for node in child.post_order():
-                yield node
+            yield from child.post_order()
         yield self
 
     def pre_order(self):
         """Return a pre-order iterator for the tree."""
         yield self
         for child in self.children:
-            for node in child.pre_order():
-                yield node
+            yield from child.pre_order()
 
     def _prefix_getter(self):
         """
         The whitespace and comments preceding this node in the input.
         """
         if not self.children:
             return ""
         return self.children[0].prefix
diff --git a/Lib/unittest/loader.py b/Lib/unittest/loader.py
--- a/Lib/unittest/loader.py
+++ b/Lib/unittest/loader.py
@@ -286,18 +286,17 @@ class TestLoader(object):
                     load_tests = getattr(package, 'load_tests', None)
                     tests = self.loadTestsFromModule(package, use_load_tests=False)
 
                 if load_tests is None:
                     if tests is not None:
                         # tests loaded from package file
                         yield tests
                     # recurse into the package
-                    for test in self._find_tests(full_path, pattern):
-                        yield test
+                    yield from self._find_tests(full_path, pattern)
                 else:
                     try:
                         yield load_tests(self, tests, pattern)
                     except Exception as e:
                         yield _make_failed_load_tests(package.__name__, e,
                                                       self.suiteClass)
 
 defaultTestLoader = TestLoader()