[Tutor] Problem with logic while extracting data from binary file

[Bryan Fodness]

Thanks again,

Still lost, even with watching the variables.  I see that it kicks out of
the loop, but don't understand what I have done to cause this.  I'm sorry
for repeated emails, but I have spent multiple days on this.  I have added
another while loop that I think should work, but I can't seem to keep it in
the while loop.  I feel like I am getting close.

It seems like it gets everything at the first level , but not the way I
expected.  It seems to get the first value inside the first while loop, and
then goes outside the loop to get the next three.  I would have expected it
to return the values as it goes through the first while loop (since they are
at the same level), then when it sees the nested identifier, go into the
second while loop and return values.

Any insight would be wonderful.

def parseSequence(data, start):
    group_num = data[start:start+2]
    element_num = data[start+2:start+4]
    vl_field = data[start+4:start+8]
    length = struct.unpack('hh', vl_field)[0]
    value = data[start+8:(start+8+length)]
    pos = start+8+length
    element = (group_num+element_num)
    if element == '\xfe\xff\x00\xe0':
        data = value
        while start < 536: #length:  # 536
            group_num = data[start:start+2]
            element_num = data[start+2:start+4]
            vl_field = data[start+4:start+8]
            length = struct.unpack('hh', vl_field)[0]
            value = data[start+8:(start+8+length)]
            start = start+8+length
            element = (group_num+element_num)
            if element == '\xfe\xff\x00\xe0':
                data = value
                while start < 112: #length:  # 112, 112, 116, 116
                    group_num = data[start:start+2]
                    element_num = data[start+2:start+4]
                    vl_field = data[start+4:start+8]
                    length = struct.unpack('hh', vl_field)[0]
                    value = data[start+8:(start+8+length)]
                    start = start+8+length
                    element = (group_num+element_num)
                    return element, start, value
            else:
                return element, start, value
    else:
        return  element, pos, value
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