title: Even Fibonacci Numbers Sum
signature: evenFibonacciNumbersSum :: Integer -> Integer
  evenFibonacciNumbersSum limit = 
source_py: def even_fibonacci_numbers_sum(limit):
      if (limit < 2):
          return 0
      ef1 = 0
      ef2 = 2
      sm = (ef1 + ef2)
      while (ef2 <= limit):
          ef3 = ((4 * ef2) + ef1)
          if (ef3 > limit):
              break
          ef1 = ef2
          ef2 = ef3
          sm = (sm + ef2)
      return sm
source_cpp: int even_fibonacci_numbers_sum(int limit) {
    if ( limit < 2 ) return 0;
    long long int ef1 = 0, ef2 = 2;
    long long int sum = ef1 + ef2;
    while ( ef2 <= limit ) {
      long long int ef3 = 4 * ef2 + ef1;
      if ( ef3 > limit ) break;
      ef1 = ef2;
      ef2 = ef3;
      sum += ef2;
    }
    return sum;
  }