class A: var = 132 def __init__(self): self.var2 = 34 a = A() setattr(a, "var", 123) setattr(a, "var2", 56) print(a.var) print(a.var2) try: setattr(a, b'var3', 1) except TypeError: print('TypeError') # try setattr on a built-in function try: setattr(int, 'to_bytes', 1) except (AttributeError, TypeError): # uPy raises AttributeError, CPython raises TypeError print('AttributeError/TypeError')