func (app *App) getEnv(name string) (bind.EnvVar, error) {
	if env, ok := app.Env[name]; ok {
		return env, nil
	}
	return bind.EnvVar{}, errors.New("Environment variable not declared for this app.")
}
func (app *App) getEnv(name string) (bind.EnvVar, error) {
	if env, ok := app.Env[name]; ok {
		return env, nil
	}
	return bind.EnvVar{}, errors.New("Environment variable not declared for this app.")
}
// getEnv returns the environment variable if it's declared in the app. It will
// return an error if the variable is not defined in this app.