https://play.golang.org/p/Qg_uv_inCek contains checks if a string is present in a slice.

New generates a new ID from the given input bytes.

PeerID is modified https://github.com/andrew-d/ptls/blob/b89c7dcc94630a77f225a48befd3710144c7c10e/ptls.go#L81.

ImproperCertsNumberError is returned from Server/Client whenever the remote peer presents a number of PeerCertificates that is not 1.

ID is the type representing a generated ID.