def __init__(self, xml=None, filename=None, length=<NUM_LIT:0>, offset=-<NUM_LIT:1>):
Jp2kBox.__init__(self)<EOL>if filename is not None and xml is not None:<EOL><INDENT>msg = ("<STR_LIT>"<EOL>"<STR_LIT>")<EOL>raise IOError(msg)<EOL><DEDENT>if filename is not None:<EOL><INDENT>self.xml = ET.parse(filename)<EOL><DEDENT>else:<EOL><INDENT>self.xml = xml<EOL><DEDENT>self.length = length<EOL>self.offset = offset<EOL>
Parameters
----------
xml : ElementTree
    An ElementTree object already existing in python.
filename : str
    File from which to read XML.  If filename is not None, then the xml
    keyword argument must be None.