我们可以编写一个 serverless framework 函数，该函数可以读取环境变量中的值并根据其值执行不同的操作。以下是一个 Node.js 代码示例，该代码示例演示了如何编写一个函数来验证环境是开发还是生产：

module.exports.environmentValidation = async (event, context) => {
  // Read the environment variable "ENVIRONMENT"
  const environment = process.env.ENVIRONMENT;
  
  // If the environment variable is not set, throw an error
  if (!environment) {
    throw new Error('The environment variable "ENVIRONMENT" is not set.');
  }
  
  // If the environment variable is set to "dev", do something
  if (environment === 'dev') {
    console.log('This is the dev environment.');
    // Do something specific to the dev environment
  }
  
  // If the environment variable is set to "prod", do something else
  else if (environment === 'prod') {
    console.log('This is the production environment.');
    // Do something specific to the production environment
  }
  
  // If the environment variable is set to something else, throw an error
  else {
    throw new Error(`The environment variable "ENVIRONMENT" has an invalid value: ${environment}`);
  }
  
  // Return a success message
  return {
    message: 'The environment is valid.',
  };
};

在这个例子中，该函数首先读取名为“ENVIRONMENT”的环境变量。如果环境变量未设置，则抛出一个错误。如果环境变量设置了不同的值（"dev" 或 "prod"）时，则会执行不同的操作。如果环境变量设置了其他值，则抛出一个错误。函数最后返回一个成功的消息。

此函数可以将其部署到开发和生产环境中，然后根据环境变量的设置来确定正在哪个环境中运行该函数。