a question about lambda

Question

heres a coding.

scores = [80,68,49,10,70,69,55]

f = lambda a :True if a<60 else False

fail = filter(f, scores)

for item in fail:
print(item)

As I set lambda a, but "a" is useless outside the lambda function, why the coding still work?

Answer 1

QTWizard I think I understand it. Thank you so much🙏🙏

Answer 2

a is an argument for f.
Like:
def f(a):
return True if a<60 else False.

Answer 3

QTWizard but when I use def, I would call the function by something like f(9), which I used the a

Answer 4

QTWizard Yes I know, but the case on the topic, it wasnt
, which still work, it seems weird

Answer 5

filter is defined like the following:
def filter(f, list0):
List1 = []
for item in list0:
if f(item): # on this line, think of item as "a"
List1.append(item)
return List1
this is not the exact implementation of filter, but i used it to show you where filter call the f function.