When I run

firebase deploy --only functions

it reads the index.js file and updates all functions exported from that file. If on the previous deploy there was a function named a, and in the current deploy there is no such function, a will be deleted.

In other words, the effect is the same as if all existing functions were deleted and then the all functions from the current index.js file were added.

Is it possible to add/update/delete individual functions?