// Unwrap returns the error wrapped in NetworkError.
func (n *NetworkError) Unwrap() error {
	return n.Err
}

// Client - http based RPC client.
type Client struct {
	connected int32 // ref: https://golang.org/pkg/sync/atomic/#pkg-note-BUG
	_         int32 // For 64 bits alignment
	lastConn  int64

	// HealthCheckFn is the function set to test for health.
	// If not set the client will not keep track of health.