formula to find the largest even in python code example

Example: return the biggest even fro a list python

b=[10,30,40,88,77,99,12515,365,959,48,8595,95,9,59,59,5,9,9,49,5,548485844842]
def is_even(lis) :
    i=len(lis)-1
    lis.sort()
    while max(lis)%2!=0:
        i=i-1
        if lis[i]%2==0:
            break
    return lis[i]
print(is_even(b))