CALLBY - set caller (parent) of a co-routine.

Usage:

B:
   callby( fcv );

C:
   void callby(void *fcv);

Where:

fcv: specifies the co-routine that will be regarded as the caller of the current co-routine.

Description:

CALLBY sets the caller attribute of the current co-routine to the co-routine specified by "fcv". A subsequent DETACH will resume the specified routine. This allows you to set your caller to some routine other than the co-routine which was established by the CALL/RESUME path to the current co-routine.