pub trait Provider<'a> {
// Required method
fn provide(&self, req: &mut Demand<'a>) -> DemandReply<()>;
// Provided method
fn provide_mut(&mut self, req: &mut Demand<'a>) -> DemandReply<()> { ... }
}
pub trait Provider<'a> {
// Required method
fn provide(&self, req: &mut Demand<'a>) -> DemandReply<()>;
// Provided method
fn provide_mut(&mut self, req: &mut Demand<'a>) -> DemandReply<()> { ... }
}