Extract all email addresses from a nested payload

Python data engineering interview problem. Difficulty: intermediate. Pattern: Recursion. About 15 minutes. Part of the Pro drill bank.

A webhook payload nests email addresses several layers down. A support tool should collect every address without the caller knowing the shape.

A privacy audit needs every email address hidden anywhere inside a nested payload: dictionaries, lists and plain values mixed together. Walk through the payload and collect all strings that look like an email address (text with an @ and a dot after it, no spaces). Return the distinct addresses as a sorted list. Write collect_emails(payload). From {'a': '[email protected]', 'b': ['no', {'c': '[email protected]'}]} the result is ['[email protected]', '[email protected]']. From {} the result is []. The starter file already has the function name and its print lines. Keep them and fill in the body.

Requirements

• Look inside every dictionary value and every list item.
• Keep only strings that match an email shape.
• Return each address once.
• Sort the result alphabetically.

Constraints

• The payload is made of dictionaries, lists and simple values.
• An address looks like [email protected] with no spaces.

Examples

Input: collect_emails({'a': '[email protected]', 'b': ['no', {'c': '[email protected]'}]}) Output: ['[email protected]', '[email protected]'] This input follows the stated rules and produces this output.

Topics: lakebench, python, nested-structures.

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