api.rs

impl AmqpClient {
  fn call(&mut self, Request::Channel::Open) -> Future<Channel, AmqpError>
}

impl Channel {
  fn declare_queue(&mut self, name: AsRef<str>) -> Future<Queue, AmqpError>
}

impl Queue {
  fn consume(&mut self) -> Future<MessageStream, AmqpError>
}

// or

impl AmqpClient {
  fn call(&mut self, Request::Channel::Open) -> Future<Channel, AmqpError>
  fn call(&mut self, Request::Channel::DeclareQueue(Channel, AsRef<str>)) -> Future<Queue, AmqpError>
  fn call(&mut self, Request::Queue::Consume(Queue)) -> Future<MessageStream, AmqpError>
}