Give the summation of all even numbers in a Fibonacci sequence up to, but not including, the maximum value.
The Fibonacci sequence is a series of numbers where the next value is the addition of the previous two values. The series starts with 0 and 1:
0 1 1 2 3 5 8 13 21...
For example:
```python
eve_fib(0)==0
eve_fib(33)==10
eve_fib(25997544)==19544084
```
def even_fib(m):
    a, b = 0, 1
    sum = 0
    while a < m:
        if a % 2 == 0:
            sum += a
        a, b = b, a + b
    return sum
def even_fib(m):
    a, b = 0, 1
    sum = 0
    while a < m:
        if a % 2 == 0:
            sum += a
        a, b = b, a + b
    return sum