def double_every_other(lst):
    """
    Takes in a list of numbers and returns a list where
    every other number is doubled.

    >>> double_every_other([5, 8, 9, 9, 8, 6, 8, 5, 7, 3, 7, 6, 5, 5, 4])
    [10, 8, 18, 9, 16, 6, 16, 5, 14, 3, 14, 6, 10, 5, 8]
    """
    for i in range(0, len(lst), 2):
        lst[i] *= 2
    return lst