coinbase.go
func OAuthClient(tokens *oauthTokens) Client {
	c := Client{
		rpc: rpc{
			auth: clientOAuth(tokens),
			mock: false,
		},
	}
	return c
}
func OAuthClient(tokens *oauthTokens) Client {
	c := Client{
		rpc: rpc{
			auth: clientOAuth(tokens),
			mock: false,
		},
	}
	return c
}
// OAuthClient instantiates the client with OAuth Authentication