`filter pred lst` returns those elements of `lst` that the predicate `pred` accepts. For example
filter (> 3) [1, 2, 3, 4, 5, 6] = [4, 5, 6]
`filter pred lst` returns those elements of `lst` that the predicate `pred` accepts. For example
filter (> 3) [1, 2, 3, 4, 5, 6] = [4, 5, 6]