RUBY_EVENT_B_CALL  583 compile.c      		ADD_TRACE(ret, FIX2INT(iseq->body->location.first_lineno), RUBY_EVENT_B_CALL);
RUBY_EVENT_B_CALL  688 vm_trace.c     	RUBY_EVENT_CALL | RUBY_EVENT_B_CALL | RUBY_EVENT_C_CALL;