Flatten Nested Config Dictionary

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Your question is Flatten Nested Config Dictionary. Start with the requirements on the right.

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Problem

At Meta, infrastructure and service configs are often represented as nested JSON-like dictionaries. Write a function that flattens a nested dictionary into a single-level dictionary using dot-separated key paths.

Given a dictionary where values may be primitives or other dictionaries, return a new dictionary mapping each leaf value to its full path. If a value is not a dictionary, it is a leaf and should appear in the output. Use . to join nested keys.

Formal Specification

Input: obj, a Python dictionary with string keys. Values may be strings, numbers, booleans, null-like values, lists, or nested dictionaries.
Output: A new dictionary where each key is the full dot-separated path to a leaf value, and each value is the original leaf value.
Empty dictionaries should contribute no entries.

Constraints

0 <= len(obj) <= 10^4 total key-value pairs across all nested dictionaries
Keys are non-empty strings and do not contain '.'
Nesting depth is at most 10^3
Values may be primitives, lists, null-like values, or nested dictionaries
Empty dictionaries should produce no flattened entry

Function Signature

def flatten_dict(obj):

Your solutionPython 3

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