Jeroen's PyVectorcall_Call from the other conversation:

C API functions are typically named as

{type or protocol}_{operation}

Now the function under discussion executes the operation Call
(it takes an args tuple and kwargs dict) and it does that using the
vectorcall protocol.

There are no PyCall_* functions so far, so creating a PyVectorCall_* is as good as a PyCall_* one.

If we wanted an existing prefix, the function could be called PyObject_VectorCall. But there's no shortage of prefixes, so no harm creating one.