title: Use multiple same header field in Lambda Proxy Integration
body: <p>I'm writing a Lambda function that returns a response for <a href="http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-create-api-as-simple-proxy-for-lambda.html" rel="nofollow noreferrer">Lambda Proxy Integration</a> in Python. The <a href="http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-set-up-simple-proxy.html#api-gateway-simple-proxy-for-lambda-output-format" rel="nofollow noreferrer">API</a> expects headers to be a dictionary.</p>
  
  <pre><code>{
      "isBase64Encoded": true|false,
      "statusCode": httpStatusCode,
      "headers": { "headerName": "headerValue", ... },
      "body": "..."
  }
  </code></pre>
  
  <p>This requires each header field to be unique, so there is no way to use multiple <code>Set-Cookie</code>'s.
  I've already tried to convert the dictionary to a list of tuples</p>
  
  <pre><code>{
      "isBase64Encoded": true|false,
      "statusCode": httpStatusCode,
      "headers": [ ("headerName": "headerValue"), ... ],
      "body": "..."
  }
  </code></pre>
  
  <p>but API gateway complains <code>Malformed Lambda proxy response</code>.</p>
  
  <p>Any idea how to set headers with the same name?</p>