/*
 *  call-seq:
 *     clause.prohibited? -> bool
 *
 *  Return true if this clause is prohibited. ie, this will be true if occur was
 *  equal to +:must_not+.
 */
static VALUE
frt_bc_is_prohibited(VALUE self)
{
    GET_BC();
    return bc->is_prohibited ? Qtrue : Qfalse;
}