def deltas(numbers):
    """
    Returns the changes between consecutive numbers in a list of numbers.

    Example: deltas([1,5,3])  ->  [4, -2]

    Parameters
    ----------
    numbers : list
        The list of numbers to process.

    Returns
    -------
    A list containing the differences between a series of numbers.
    """
    return [l - r for l,r in zip(numbers[1:], numbers[:])]