func NewClient(xp Transporter, u ErrorUnwrapper,
	tagsFunc LogTagsFromContext) *Client {
	return &Client{xp, u, tagsFunc, nil}
}
NewClient constructs a new client from the given RPC Transporter and the
ErrorUnwrapper.
package rpc
import (
	"errors"
	"time"
	"golang.org/x/net/context"
)
type Client struct {
	xp             Transporter
	errorUnwrapper ErrorUnwrapper
	tagsFunc       LogTagsFromContext
	sendNotifier   SendNotifier
}