parse an XML in-memory document and build a tree. This
           reuses the existing @ctxt parser context

def ctxtReadMemory(self, buffer, size, URL, encoding, options):
        """parse an XML in-memory document and build a tree. This
           reuses the existing @ctxt parser context """
        ret = libxml2mod.xmlCtxtReadMemory(self._o, buffer, size, URL, encoding, options)
        if ret is None:raise treeError('xmlCtxtReadMemory() failed')
        __tmp = xmlDoc(_obj=ret)
        return __tmp