const apiKey = '<OpenAI's APIKey>';
const {data} = await axios.post("https://api.openai.com/v1/chat/completions", {
  "model": "gpt-3.5-turbo-0301",
  "messages": [{"role": "user", "content": event.preview}]
}, { headers: {'Authorization': `Bearer ${apiKey}`}});

workflow.variableName = data.choices[0].message.content;