I'm just hanging out and trying freecodecamp lambda built-in function for code exercise using Learn Lambda Functions by Building an Expense Tracker python course section...

lambda expense: expense['amount'], expenses)` 

So, lambda x: x * 2 is an example which is obvious... then

lambda expense: expense['category'] == category is a usage for filtering out mechanism usage scenario as an example:

expense1 = {'amount': 10, 'category': 'Food'}
expense2 = {'amount': 20, 'category': 'Travel'}

category = 'Food'

check = lambda expense: expense['category'] == category

print(check(expense1))  # True  → true
print(check(expense2))  # False → exact violation and filtering out

This is the way of boolean mechanism to create filtering effect just for list, tuples, dictionaries etc. ...

I'm asking just for any other usage scenario whether or not, what would be? Cause this boolean needs look-up table- I mean outer constraints (dependency). In the given scenario an outer value requirement is exist. By itself the boolean mechanism seems useless but it seems and I don't know maybe there would be very useful in the boolean equality check context...

But are there practical scenarios where boolean using the equality operator checking lambdas are useful when they DON'T depend on external variables? What are common use cases for self-contained boolean lambda functions?