API:UnitIsUnit

Determines whether two given units refer to one and the same unit.

Arguments

 * UnitId1
 * string - The first UnitId.
 * UnitId2
 * string - The second UnitId.

Returns

 * boolean
 * Boolean value -  if both UnitId refer to the same unit,   otherwise.
 * will be returned if the target UnitId does not exist (see Example 2).