code: def parseEntity(filename):
      
      ret = libxml2mod.xmlParseEntity(filename)
      if ret is None:raise parserError('xmlParseEntity() failed')
      return xmlDoc(_obj=ret)
docs: parse an XML external entity out of context and build a
        tree.  [78] extParsedEnt ::= TextDecl? content  This
         correspond to a "Well Balanced" chunk