Fredrik Lundh once suggested the following set of rules for refactoring uses of lambda:
- Write a lambda function.
- Write a comment explaining what the heck that lambda does.
- Study the comment for a while, and think of a name that captures the essence of the comment.
- Convert the lambda to a def statement, using that name.
- Remove the comment.
I really like these rules, but you’re free to disagree about whether this lambda-free style is better.
from the python docs