Function mrb_define_class_under 

pub unsafe extern "C" fn mrb_define_class_under(
    mrb: *mut mrb_state,
    outer: *mut RClass,
    name: *const c_char,
    super_: *mut RClass,
) -> *mut RClass

Defines a new class under a given module

@param mrb The current mruby state. @param outer Reference to the module under which the new class will be defined @param name The name of the defined class @param super The new class parent @return [struct RClass *] Reference to the newly defined class @see mrb_define_class