API UnitIsUnit

Returns true if the specified units are the same unit.
 isSame = UnitIsUnit(unit1, unit2)
==Arguments==
:;unit1: : UnitId - The first unit to query (e.g. "party1", "pet", "player")
:;unit2: : UnitId - The second unit to compare it to (e.g. "target")
==Returns==
:;isSame: - 1 if the two units are the same entity, nil otherwise.
==Example==
 if ( UnitIsUnit("targettarget", "player") ) then
 message("Look at me, I have aggro from " .. UnitName("target") .. "!");
 end;
===Result===
Displays a message if your target is targetting you.