// Sum the numbers in a list.
F.sum([1, 2, 3]); // 6

// Stash a string.
F.map(F.surround('{', '}'), 'hello'); // '{h}{e}{l}{l}{o}'

// Intersperse the numbers in a list with another number.
F.intersperse(4, [1, 2, 3]); // [1, 4, 2, 4, 3]

// Filter the numbers in a list where 1 < n < 5.
[1, 2, 3, 4, 5].filter(F.whereAll([F.gt(1), F.lt(5)])); // [2, 3, 4]

// Calculate the cartesian product of two lists.
F.cartesian([1, 2], [3, 4]); // [[1, 3], [1, 4], [2, 3], [2, 4]]

// Calculate the permutations of a list.
F.permutations('abc'); // ['abc', 'bac', 'cba', 'bca', 'cab', 'acb']