Mocking python function based on input arguments

We have been using Mock for python for a while.

Now, we have a situation in which we want to mock a function

def foo(self, my_param):
    #do something here, assign something to my_result
    return my_result

Normally, the way to mock this would be (assuming foo being part of an object)

self.foo = MagicMock(return_value="mocked!")

Even, if i call foo() a couple of times i can use

self.foo = MagicMock(side_effect=["mocked once", "mocked twice!"])

Now, I am facing a situation in which I want to return a fixed value when the input parameter has a particular value. So if let’s say “my_param” is equal to “something” then I want to return “my_cool_mock”

This seems to be available on mockito for python

when(dummy).foo("something").thenReturn("my_cool_mock")

I have been searching on how to achieve the same with Mock with no success?

Any ideas?