Remove dead code clearsky._is_leap_year

[JoLo90]

The following internal functions or methods aren't used in the pvlib codebase

pvlib-python/pvlib/clearsky.py

Line 223 in 5f70c5a

def _is_leap_year(year):

pvlib-python/pvlib/modelchain.py

Line 1251 in 5f70c5a

def _prep_inputs_tracking(self):

Should we remove them in a future version ?

[cwhanse]

I concur with these removals.

def _prep_inputs_tracking(self):

This private function was added before the author (me) of the run_model PR realized that tracking computations are expected to be done prior to instantiating the PVSystem that ModelChain operates on.

ModelChain is clumsy for tracking PV systems. Different issue to improve it.

[cwhanse]

Second thoughts: let's remove _is_leap_year and keep _prep_inputs_tracking. I'd like to open a new issue to smooth out ModelChain methods for tracking systems, and that function might be needed.

[dgowdaan-cmyk]

Hi! I can take this.

I'll remove the _is_leap_year function from pvlib/clearsky.py since it's unused, and verify there are no references to it elsewhere in the codebase.
I'll also add a test to confirm nothing breaks.

Let me know if you'd like me to proceed.

[cwhanse]

@dgowdaan-cmyk go ahead please. No need to deprecate or to add a new test.