LFUN
  #include <classes.h>

  string * AddClassId (string id)
  string * AddClassId (string * id)

DESCRIPTION
  Add one or more id strings to this object's P_CLASS_IDS.

  Argument:
    id: a single string, or an array of strings to add.

  Result: P_CLASS_IDS' new content.

EXAMPLE
  AddClassId ("button");
  AddClassId (C_WEAPON);

IMPLEMENTED
  /std/thing/description