Package backoff implement the backoff strategy for gRPC.
This is kept in internal until the gRPC project decides whether or not to allow alternative backoff strategies.
Exponential implements exponential backoff algorithm as defined in https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
Backoff returns the amount of time to wait before the next retry given the number of retries.
Strategy defines the methodology for backing off after a grpc connection failure.