<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse(cls, fptr, offset, length):
 """Parse JPEG 2000 color specification box. Parameters fptr : file Open file object. offset : int Start position of box in bytes. length : int Length of the box in bytes. Returns ------- ColourSpecificationBox Instance of the current colour specification box. """

        num_bytes = offset + length - fptr.tell()
        read_buffer = fptr.read(num_bytes)

        lst = struct.unpack_from('>BBB', read_buffer, offset=0)
        method, precedence, approximation = lst

        if method == 1:
            # enumerated colour space
            colorspace, = struct.unpack_from('>I', read_buffer, offset=3)
            if colorspace not in _COLORSPACE_MAP_DISPLAY.keys():
                msg = "Unrecognized colorspace ({colorspace})."
                msg = msg.format(colorspace=colorspace)
                warnings.warn(msg, UserWarning)
            icc_profile = None

        else:
            # ICC profile
            colorspace = None
            if (num_bytes - 3) < 128:
                msg = ("ICC profile header is corrupt, length is "
                       "only {length} when it should be at least 128.")
                warnings.warn(msg.format(length=num_bytes - 3), UserWarning)
                icc_profile = None
            else:
                profile = _ICCProfile(read_buffer[3:])
                icc_profile = profile.header

        return cls(method=method,
                   precedence=precedence,
                   approximation=approximation,
                   colorspace=colorspace,
                   icc_profile=icc_profile,
                   length=length,
                   offset=offset)