If I had a program where calculating distance between points on earth was important and I had an API with a function called earthDistance, then knowing that it

If I had a program where calculating distance between points on earth was important and I had an API with a function called earthDistance, then knowing that it was actually calculating the Haversine distance would be vital knowledge, since that approach is known to give quite high errors and that I should avoid using that function if I care about accuracy.