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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def parse(cls, fptr, offset, length):
 """Parse JPEG 2000 signature box. Parameters fptr : file Open file object. offset : int Start position of box in bytes. length : int Length of the box in bytes. Returns ------- JPEG2000SignatureBox Instance of the current JPEG2000 signature box. """

        read_buffer = fptr.read(4)
        signature = struct.unpack('>BBBB', read_buffer)

        return cls(signature=signature, length=length, offset=offset)