Name Errors

A NameError means Python tried to use a name that does not exist in the current scope.

Python knows score. It does not know scores.

This is one of the most useful early errors because it usually points to a small problem:

• a typo;
• a name used before assignment;
• a name created only inside a branch that did not run;
• a local name used outside its function.

Typo in a name

The fix is not conceptual. It is spelling:

Used before assignment

Python runs top to bottom:

The assignment happens too late. Move the assignment before the use.

Created only in one branch

If the condition is false, label is never created.

A clearer version assigns a value in every path:

Local names stay local

Names created inside a function belong to that call:

The name label inside the function is not available outside. Use the return value: