What does **variable do in Python?

In Python, **variable is used in two primary ways depending on the context:

1. Unpacking Keyword Arguments in Function Definitions (**kwargs):

In a function definition, **variable (commonly named **kwargs, but it can be any valid variable name) is used to collect keyword arguments into a dictionary. This allows the function to accept an arbitrary number of keyword arguments.

Example:

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def print_info(**kwargs):

    for key, value in kwargs.items():

        print(f"{key}: {value}")

# Call the function with arbitrary keyword arguments

print_info(name="John", age=30, location="New York")

Output:

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name: John

age: 30

location: New York

In this case, the **kwargs collects the keyword arguments (name="John", age=30, etc.) into a dictionary:

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kwargs = {'name': 'John', 'age': 30, 'location': 'New York'}

2. Unpacking a Dictionary into Keyword Arguments (** in function calls):

In a function call, **variable is used to unpack a dictionary so that its key-value pairs are passed as keyword arguments to the function.

Example:

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def greet(name, age):

    print(f"Hello, my name is {name} and I am {age} years old.")

person = {"name": "Alice", "age": 25}

# Unpacking the dictionary

greet(**person)

Output:

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Hello, my name is Alice and I am 25 years old.

Here, **person unpacks the dictionary into name="Alice" and age=25, which are passed as keyword arguments to the greet function.

Summary:

In function definitions, **kwargs allows collecting an arbitrary number of keyword arguments into a dictionary.

In function calls, **variable allows unpacking a dictionary into keyword arguments, making it easy to pass a dictionary's contents as function arguments.