Returns whether a unit exists. A unit "exists" if it can be referenced by the player; e.g.
party1 exists if the player is in a party with at least one other member (regardless of whether that member is nearby),
target exists if the player has a target,
npc exists if the player is currently interacting with an NPC, etc.
See also Unit functions.
unit- A unit to query (
name- The name of a unit to query; only valid for
npc, and party/raid members (
exists- 1 if the unit exists, otherwise nil (