Parameter objects are immutable. Instead of modifying a Parameter object, you can use Parameter.replace() to create a modified copy.
class inspect.Parameter(name, kind, *, default=Parameter.empty, annotation=Parameter.empty)>>> def foo(a, b, *, c, d=10):
... pass
>>> sig = signature(foo)
>>> for param in sig.parameters.values():
... if (param.kind == param.KEYWORD_ONLY and
... param.default is param.empty):
... print('Parameter:', param)
Parameter: c>>> def foo(a, b, *, c, d=10):
... pass
>>> sig = signature(foo)
>>> for param in sig.parameters.values():
... print(param.kind.description)
positional or keyword
positional or keyword
keyword-only
keyword-only>>> from inspect import Parameter
>>> param = Parameter('foo', Parameter.KEYWORD_ONLY, default=42)
>>> str(param)
'foo=42'
>>> str(param.replace()) Will create a shallow copy of 'param'
'foo=42'
>>> str(param.replace(default=Parameter.empty, annotation='spam'))
"foo: 'spam'"