/**
 * @param config {object} environment config object
 * 
 * {
 *   [serviceName]: {
 *     [key]: "{value}",
 *     ...
 *   },
 *   ...
 * }
 **/
function generateCommand(config) {
  let list = [];
  for(let [serviceName, serviceObject] of Object.entries(config)) {
    for (let [key, value] of Object.entries(serviceObject)) {
      list.push(`${serviceName}.${key}="${value}"`);
    }
  }
  return `firebase functions:config:set ${list.join(" ")}`;
}