CPython functions that use PyArg_ParseTuple() to parse their arguments do not support keyword arguments (mostly because PyArg_ParseTuple()
only supports positional parameters, e.g. a simple sequence).
This is explained in the CPython implementation details
here:
CPython implementation detail: An implementation may provide built-in functions whose positional parameters do not have names, even if they are ‘named’ for the purpose of documentation, and which therefore cannot be supplied by keyword. In CPython, this is the case for functions implemented in C that use
PyArg_ParseTuple()
to parse their arguments.