[Tutor] Need help with structure unpacking module

[Nirmal Sakthi]

I am using module struct.unpack() to decode data from a binary file, so that
I can use the value in a calculation.

I have been able to extract an integer value.

     >>>length = struct.unpack('i', '\x9c\x00\x00\x00')
     >>>length = int(length[0])
     >>>print length
     156

I want to be able to extract a string.

I have tried,

    >>>first = struct.unpack('s', '\x02\x00')
    >>>first = str(first[0])
    >>>print first
    Traceback (most recent call last):
......
    error: unpack requires a string argument of length 1
and,

    >>>first = struct.unpack('cccc', '\x02\x00')
    >>>first = str(first[0])
    >>>print first
     Traceback (most recent call last):
......
         return o.unpack(s)
     error: unpack requires a string argument of length 4

My desired result would be the string  '0200'.  Actually, I would like to be
able to invert the bytes to get '0002'.
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