__closure__ magic function in Python
Almost everything in Python is an object, similarly function is an object too and all the function objects have a __closure__ attribute. __closure__ is a dunder/magic function i.e. methods having two underscores as prefix and suffix in the method name
A closure is a function object that remembers values in enclosing scopes even if they are not present in memory. The __closure__ attribute of a closure function returns a tuple of cell objects. This cell object also has an attribute called cell_contents, which returns returns the contents of the cell.
(<cell at 0x7f34ba2725e0: int object at 0x7f34bde02720>,)
In the above example, the nested function power has __closure__ attribute associated with it and it returns a tuple of cell objects. The cell_contents attribute returns the value 3 as it was closed inside the cell object.