Suma sekwencji
// Your task is to make function, which returns the sum of a sequence of integers.
// The sequence is defined by 3 non-negative values: begin, end, step (inclusive).
// If begin value is greater than the end, function should returns 0
const sequenceSum = (begin, end, step) => {
let sum = 0;
for(let i = begin; i <= end; i += step) sum += i;
return sum;
};
// With love @kouqhar
kouqhar