QUEUE AS AN ADT

Abstract typedef<> queue(eltype)
abstract empty(q)
queue (eltype)q;
Post condition empty = = ( len(q)= =0);

abstract queue insert (q,elt)
queue eltype)q;
post condition q=p +

abstract queue remove(q,elt)
queue(empty)q;
pre condition empty(q)= = FALSE;
post condition remove = = first(q)
q = = sub(q,1,len(q)-1)