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README.rst

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 How does it work?
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 The `constable.trace` decorator uses Python's Abstract Syntax Tree (AST) in much the same way we add `print`(s) to debug states. During runtime, it prepares and inserts `print` statements into the function's AST after every assignment operation (`ast.Assign`, `ast.AugAssign` and `ast.AnnAssign`), and then executes the modified code in a separate namespace with `exec`.