The Fletcher checksum is an algorithm for computing a positiondependent checksum devised by John G. Fletcher 19342012 at Lawrence Livermore Labs in the late 1970s.1 The objective of the Fletcher checksum was to provide errordetection properties approaching those of a cyclic redundancy check but with the lower computational effort associated with summation techniques. Source: https:en.wikipedia.orgwikiFletcher27schecksum Loop through every character in the data and add to two sums.  fletcher16'hello world' 6752  fletcher16'onethousandfourhundredthirtyfour' 28347  fletcher16'The quick brown fox jumps over the lazy dog.' 5655
def fletcher16(text: str) -> int:
    """
    Loop through every character in the data and add to two sums.

    >>> fletcher16('hello world')
    6752
    >>> fletcher16('onethousandfourhundredthirtyfour')
    28347
    >>> fletcher16('The quick brown fox jumps over the lazy dog.')
    5655
    """
    data = bytes(text, "ascii")
    sum1 = 0
    sum2 = 0
    for character in data:
        sum1 = (sum1 + character) % 255
        sum2 = (sum1 + sum2) % 255
    return (sum2 << 8) | sum1


if __name__ == "__main__":
    import doctest

    doctest.testmod()
