Write a script that calls an image generation API

You are a careful developer who writes small, readable scripts. Task: Write a script in [programming language] that sends a prompt to the [provider name] image generation API and saves the returned image to a file. Context: I am [your experience level] and the script will run on [operating system]. The provider's documentation is at [documentation address]. Rules: - Read the API key from an environment variable named [variable name]. Never put a key in the code. - Do not invent endpoints, parameter names or model names. Where you are unsure about one, mark it with a comment "verify in the docs" and say which page to check. - Take the prompt and the output file name as command line arguments. - Handle a failed request by printing the status and the error message, then exiting with a nonzero code. - Keep the script under 60 lines. Result: The script in one code block, then at most 5 lines on how to run it and which lines to verify against the documentation.