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What is the use of the "is" keyword in Python?

In Python, the is keyword is used to compare whether two objects or variables refer to the same object in memory. It checks for object identity rather than comparing the values of the objects.

Here are some key points about the is keyword:

  • The is keyword evaluates to True if both operands point to the same object in memory, and False otherwise.
  • It is used to check if two variables or objects refer to the same memory location, indicating that they are the same object.
  • It is commonly used to compare object references, such as checking if two variables point to the same instance of a class or if an object is None.
  • Unlike the == operator, which compares the values of objects, the is keyword checks for object identity.

Here's an example to illustrate the usage of the is keyword:

x = [1, 2, 3]
y = [1, 2, 3]
z = x

print(x is y)  # False - Different objects
print(x is z)  # True - Same object

Output:

False
True

In the example above, two lists, x and y, are created with the same values. Although the values of the lists are the same, they are distinct objects with different memory locations. Hence, x is y evaluates to False. On the other hand, the z variable is assigned to the same object as x, so x is z evaluates to True.

It's important to note that the is keyword should not be used for comparing equality or equivalence of objects. For value-based comparisons, you should use the == operator, which compares the values of objects rather than their identities.

In summary, the is keyword in Python is used to check whether two objects or variables refer to the same object in memory. It is useful for comparing object identities, such as checking if two variables point to the same object instance.

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