API UnitExists

__NOTOC__
Returns true if the unit exists.
 exists = UnitExists(unit)
==Arguments==
:;unit: : UnitId
==Returns==
:;exists: - true if the unit exists and is in the current zone, or false if not
==Example==
The snippet below prints a message describing what the player is targeting.
 if UnitExists("target") then
 print("You're targeting a " .. UnitName("target"))
 else
 print("You have no target")
 end