Не получается определить функцию внутри 'exec'

The default locals act as described for function locals() below: modifications to the default locals dictionary should not be attempted. Pass an explicit locals dictionary if you need to see effects of the code on locals after function exec() returns.

  3           0 LOAD_GLOBAL              0 (exec)
              3 LOAD_CONST               1 ('f = lambda x: x')
              6 CALL_FUNCTION            1
              9 POP_TOP

  4          10 LOAD_GLOBAL              1 (print)
             13 LOAD_GLOBAL              2 (f)
             16 LOAD_CONST               2 (1)
             19 CALL_FUNCTION            1
             22 CALL_FUNCTION            1
             25 POP_TOP
             26 LOAD_CONST               0 (None)
             29 RETURN_VALUE

  3           0 LOAD_CONST               1 ('f = lambda x: x')
              3 LOAD_CONST               0 (None)
              6 DUP_TOP
              7 EXEC_STMT

  4           8 LOAD_NAME                0 (f)
             11 LOAD_CONST               2 (1)
             14 CALL_FUNCTION            1
             17 PRINT_ITEM
             18 PRINT_NEWLINE
             19 LOAD_CONST               0 (None)
             22 RETURN_VALUE

>>> class A:
...     def __init__(self):
...         exec('f = lambda x: x', globals())
...         print(f(1))
...
>>> a = A()
1

def boo():
    exec('foo = "bar"')
    print(locals())

boo()

class A:
    def __init__(self):
        exec('f = lambda x: x')
        g = locals()['f']
        print(g(1))

a = A()

class A:
    def __init__(self):
        exec('f = lambda x: x')
        f = locals()['f']
        print(f(1))

a = A()

Traceback (most recent call last):
  File "test.py", line 7, in <module>
    a = A()
  File "test.py", line 4, in __init__
    f = locals()['f']
KeyError: 'f'

def boo():
    d = locals()
    exec('foo = "bar"', globals(), d)
    foo = d['foo']
    print(foo)

boo()

import yaml
yaml.dump(lambda x,y,z: x+y+z)

"!!python/name:__main__.%3Clambda%3E ''\n"

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.2/site-packages/yaml/__init__.py", line 200, in dump
    return dump_all([data], stream, Dumper=Dumper, **kwds)
  File "/usr/lib64/python3.2/site-packages/yaml/__init__.py", line 188, in dump_all
    dumper.represent(data)
  File "/usr/lib64/python3.2/site-packages/yaml/representer.py", line 27, in represent
    self.serialize(node)
  File "/usr/lib64/python3.2/site-packages/yaml/serializer.py", line 54, in serialize
    self.serialize_node(node, None, None)
  File "/usr/lib64/python3.2/site-packages/yaml/serializer.py", line 90, in serialize_node
    style=node.style))
  File "/usr/lib64/python3.2/site-packages/yaml/emitter.py", line 115, in emit
    self.state()
  File "/usr/lib64/python3.2/site-packages/yaml/emitter.py", line 228, in expect_document_root
    self.expect_node(root=True)
  File "/usr/lib64/python3.2/site-packages/yaml/emitter.py", line 242, in expect_node
    self.process_tag()
  File "/usr/lib64/python3.2/site-packages/yaml/emitter.py", line 489, in process_tag
    self.prepared_tag = self.prepare_tag(tag)
  File "/usr/lib64/python3.2/site-packages/yaml/emitter.py", line 607, in prepare_tag
    chunks.append('%%%02X' % ord(ch))
TypeError: ord() expected string of length 1, but int found

def boo():
    exec('foo = "bar"')
    print(locals())
    print(foo)

boo()

>>> boo()
{'foo': 'bar'}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in boo
NameError: global name 'foo' is not defined