// https://projecteuler.net/problem=2

// <p>Each new term in the Fibonacci sequence is generated by adding the previous 
// two terms. By starting with $1$ and $2$, the first $10$ terms will be: 
// $$1, 2, 3, 5, 8, 13, 21, 34, 55, 89, \dots$$</p>
// <p>By considering the terms in the Fibonacci sequence whose values do not exceed
// four million, find the sum of the even-valued terms.</p>