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Builtin function are function that doesn't need an import statement.
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Namespace
The builtins namespace associated with the execution of a code block is actually found by looking up the name __builtins__ in its global namespace
By default, when in the main module, __builtins__ is the built-in module builtins; when in any other module, __builtins__ is an alias for the dictionary of the builtins module itself.