code: function applyEnv(env, secrets = {}, required = {}) {
    if (Array.isArray(env)) {
      env.forEach(key => {
        // if the key already exists don't overwrite it
        if (!process.env[key]) {
          const value = getValue(key, {}, secrets, required)
          process.env[key] = value
        }
      })
    } else {
      Object.entries(env).forEach(([key, value]) => {
        // if the key already exists don't overwrite it
        if (!process.env[key]) {
          const value = getValue(key, env, secrets, required)
          process.env[key] = value
        }
      })
    }
  }
docs: Apply the environment variables to `process.env`
  @param  {Object} env      Map of environment variables
  @param  {Object} secrets  Map of secrets
  @param  {Object} required Map of required values