Quick Answer

Handle undefined name references.

Understanding the Issue

Python raises NameError when trying to access a variable or function that hasn't been defined in the current scope.

The Problem

This code demonstrates the issue:

Python Error 
print(undefined_var)  # Error

The Solution

Here's the corrected code:

Python Fixed 
# Solution 1: Define variable first
defined_var = "value"
print(defined_var)

# Solution 2: Check variable scope
def function():
    local_var = "test"
    print(local_var)
# print(local_var) would fail outside function

# Solution 3: Verify imports
from module import needed_function

# Solution 4: Exception handling
try:
    print(maybe_defined)
except NameError:
    print("Variable not defined")

Key Takeaways

Ensure names are defined before use and understand Python's scoping rules.