def GetTopicsTree(self):
if self.topics is None:<EOL><INDENT>return None<EOL><DEDENT>if self.topics:<EOL><INDENT>res, ui = chmlib.chm_resolve_object(self.file, self.topics)<EOL>if (res != chmlib.CHM_RESOLVE_SUCCESS):<EOL><INDENT>return None<EOL><DEDENT><DEDENT>size, text = chmlib.chm_retrieve_object(self.file, ui, <NUM_LIT:0>, ui.length)<EOL>if (size == <NUM_LIT:0>):<EOL><INDENT>sys.stderr.write('<STR_LIT>')<EOL>return None<EOL><DEDENT>return text<EOL>
Reads and returns the topics tree.
        This auxiliary function reads and returns the topics tree file
        contents for the CHM archive.