New constructs an empty Chain.

Chain represents a "chain" of middlewares through which a request can be threaded.

Handler is like http.HandlerFunc, but returns an error indicating a failure during process the request.

Middleware is a function that takes a Handler and returns a Handler It describes a transformation on the request/response Middleware can short-circuit the chain by not calling the passed in handler.

TerminatingMiddleware should sit at the top of the middleware chain, and converts a Handler (which returns an error) into a standard http.HandlerFunc which can be given to things like mux.Router.