Adding parameters to get_template_part( );

I would like to add an extra parameter to this function.

ie I want a loop-format.php to be called with a parameter that is unique to each query (category for instance)

I can use;
$parameter = ‘something’;
include(locate_template(‘loop-course.php’));

=and then handle $parameter within the include

but that’s just a bit ugly (and I would guess inefficient – I have called it 8 times in one template)

I would like to write;
get_template_part( ‘loop’, ‘course’, ‘something’);

I need a filter to add this to the built-in function. But how do I do this?