Function mrb_fiber_yield 

pub unsafe extern "C" fn mrb_fiber_yield(
    mrb: *mut mrb_state,
    argc: mrb_int,
    argv: *const mrb_value,
) -> mrb_value

Yield a Fiber

Implemented in mruby-fiber

Passes control to the caller fiber of the running fiber. Like the Fiber.yield method.

@note This function is only available from inside a function defined as a method by, for example, mrb_define_method(). Also, the work following mrb_fiber_yield() cannot be performed, and the return value of mrb_fiber_yield() must be returned as is.

      return mrb_fiber_yield(mrb, argc, argv);