Filter in Python
Filter is a built-in first class function that performs a function on a sequence, and removes all sequence elements where the function returned 'false'.
filtered_sequence = filter(function, unfiltered_sequence)
In Python 2, the filter function returns a list by default. In Python 3, the filter function returns an iterator, which must be wrapped into a list if that's the desired result.
Like all first class functions, filters are most often used with lambdas.
grades = [35, 80, 50, 60] passed = list(filter(lambda grade: grade >= 50, grades)) #should return [80, 50, 60]