In PEP 8, from The quick python book.

1. Module/package names - short lower case, underscores only if needed
2. Function names - all lowercase, underscores for readability
3. Variable names - all lowercase, underscores for readability
4. Class names - capitalise each word
5. Constant names - all caps with underscores
6. Indentation - 4 spaces, no tabs
7. Comparisons - don’t compare explicitly to true or false