Can you list the main namespaces in Python and explain their purpose?

In Python, there are three main namespaces that define the scope of objects:

1. Local namespace — contains names defined inside the current function or method. These names are only accessible within that function.

2. Enclosing namespace — the namespace of outer functions if a function is nested inside another. It allows nested functions to access variables from the outer function.

3. Global namespace — contains names defined at the module level (file). Accessible throughout the module.

4. Built-in namespace — contains names of Python's built-in functions and exceptions, such as print(), len(), Exception.

Python searches for a name in LEGB order: Local, Enclosing, Global, Built-in.

Example:

x = 'global'

def outer():
    x = 'enclosing'
    def inner():
        x = 'local'
        print(x)  # prints 'local'
    inner()
    print(x)  # prints 'enclosing'

outer()
print(x)  # prints 'global'