code: func OAuthService(clientId string, clientSecret string, redirectUri string) (*OAuth, error) {
  	certFilePath := basePath + "/ca-coinbase.crt"
  	serviceAuth, err := serviceOAuth(certFilePath)
  	if err != nil {
  		return nil, err
  	}
  	o := OAuth{
  		ClientId:     clientId,
  		ClientSecret: clientSecret,
  		RedirectUri:  redirectUri,
  		Rpc: rpc{
  			auth: serviceAuth,
  			mock: false,
  		},
  	}
  	return &o, nil
  }
docs: // OAuthService Instantiates OAuth Struct in order to send service related OAuth requests