How to fix Name Not Defined Error in Python?

 To fix a "NameError: name 'variable_name' is not defined" error in Python, you can take the following steps:

1. Check variable name spelling: Make sure you have spelled the variable name correctly. Python is case-sensitive, so ensure that the case matches exactly.

2. Check variable scope: Verify that the variable is defined in the appropriate scope. If you're trying to access a variable defined inside a function, for example, ensure that you're accessing it within that function or in a wider scope where it's visible.

3. Check variable assignment: If you're trying to use a variable before it has been assigned a value, you will encounter a NameError. Make sure the variable is assigned a value before you attempt to use it.

4. Check import statements: If you're working with modules or packages, ensure that you have imported them correctly. Verify that the module or package name is correct and that you have imported it using the appropriate import statement.

5. Check code execution order: If you're referencing a variable in a different part of your code than where it was defined, ensure that the code defining the variable is executed before the code that uses it.

6. Check for typos or missing symbols: Look for any typos or missing symbols in your code, such as missing parentheses, colons, or quotation marks. These errors can lead to a NameError if the code is not properly formatted.

7. Check function calls: If you're encountering a NameError related to a function, verify that you're calling the function with the correct name and arguments.

8. Run the code in a fresh environment: If you've made recent changes to your code and are encountering a NameError, try running the code in a fresh environment or restarting your Python interpreter. Sometimes, cached or outdated variables can cause issues.

By following these steps, you should be able to identify and resolve most "NameError: name 'variable_name' is not defined" errors in your Python code.