// Determines the number of times that oCreature has nSpell memorised.
// - nSpell: SPELL_*
// - oCreature
int GetHasSpell(int nSpell, object oCreature=OBJECT_SELF);

NOTE: When using this function on a wizard or cleric and checking for summon creature spells, 1-9 it works very wonky. 1) It will only look at level 1 spell slots. 2) It will only look at spell slots occupied. 3) The output result is calculated by the following strange formula:

   Sum of the squares of similar spells.  To clarify:

Let's say I have 5 level 1 spell slots. If each spell in the 5 slots is unique, output is 5. If I have 5 magic missiles prepared, output is 25. If I have 3 magic missiles and 2 Charm Peron spells, output is 3^2 + 2^2 = 13 This strange formula is used ONLY when checking whether the cleric or wizard has summon creature spells 1-9