u : A unit to be examined.
 i : An id of an affect, see ID_* in values.h and/or vme.h
 result: TRUE, if unit 'u' is affected by affect id 'i'

Examples:

 if (isaff(self, ID_BLIND_CHAR))
   sendtext("You're blinded", self);

This command scans the unit 'u' for any affect matching the id 'i' and returns TRUE if one is found.

See also:

 > subaff()
 > addaff()
 > getaffects()