# Setup: in global scope, use a comprehension with colliding variable name
foo = None
[foo for foo in [0]]

# Repro: assigning to frame.f_locals and then merging to fast works only the first time
import inspect, ctypes
frame = inspect.currentframe()

frame.f_locals['a'] = 1
ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(frame), ctypes.c_int(0))
print(a)  # 1

frame.f_locals['b'] = 2
ctypes.pythonapi.PyFrame_LocalsToFast(ctypes.py_object(frame), ctypes.c_int(0))
print(b)  # NameError: name 'b' is not defined