From the NannyMUD documentation

LAST CHANGE

2000-12-19

FUNCTION

NAME
        set_light - Add to/query the light level of the current	object.


NOTE
	This sfun is OBSOLETE, use add_light and query_light instead.


SYNTAX
	int set_light(int l)

DESCRIPTION
	An object is by default dark. It can be set to not dark by calling
	set_light(1). The environment will the also get this light.  The
	returned value is the total number of lights in this room.

	You can set the object to be 'more than dark' by using negative
	values.


NOTE
	set_light() can be called in other objects.
	The argument is added to the light of the object.


EXAMPLE
	set_light(0) 
	   return the current light level
 
	set_light(1) 
	  make this object somewhat lighter

	set_light(1, ob)
	  make ob somewhat lighter.

	set_light(-set_light(0))
	  Lights out.


SEE ALSO
        add_light in sfun/add_light


SEE ALSO
        query_light in sfun/query_light