Expert guidance for writing Python code in n8n Code nodes, with strong recommendation to use JavaScript instead.

• Python is limited to standard library only (json, datetime, re, base64, hashlib, urllib.parse, math, random, statistics); no external packages like requests, pandas, or numpy
• Must return data as a list of dictionaries with {"json": {...}} structure; common mistakes include incorrect return format, missing return statements, and unsafe dictionary access without .get()
• Two execution modes available: "Run Once for All Items" (recommended, uses _input.all()) and "Run Once for Each Item" (uses _input.item); webhook data is nested under _json["body"], not at root level
• Use Python only when you need specific standard library functions or are significantly more comfortable with Python syntax; JavaScript is preferred for 95% of use cases due to better n8n helper functions and documentation