When using the following library[1] I experienced a weird error:

Frozen module / copied into some importable path makes no difference.
I'm having the following interaction with the repl:

>>> from mp_modbus_master import modbus_rtu_master
>>> modbus_rtu_master()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/TMP/mp_modbus_master.py", line 513, in __init__
TypeError: unexpected keyword argument 'rtu'
>>>

Looking at the code, though, (https://github.com/eydam-prototyping/mp_modbus/blob/master/mp_modbus_master.py#L513) there's no kwarg rtu.
The only occurrence of the string "rtu" is the default value to the kwarg ms_type in that line.
That this string "rtu" is indeed the one seen as kwarg by mpy is confirmed by changing it to "XXX" - whereas mpy then complains about TypeError: unexpected keyword argument 'XXX'

Minimal test case showing this behaviour (thanks to @jimmo):

def a(x="y"):
    print(x)

def b(*args):
    a(x="z", *args)

b()

resulting in

Traceback (most recent call last):
  File "<stdin>", line 7, in <module>
  File "<stdin>", line 5, in b
TypeError: unexpected keyword argument 'z'

[1]https://github.com/eydam-prototyping/mp_modbus