code: def regexpCompile(regexp):
      
      ret = libxml2mod.xmlRegexpCompile(regexp)
      if ret is None:raise treeError('xmlRegexpCompile() failed')
      return xmlReg(_obj=ret)
docs: Parses a regular expression conforming to XML Schemas Part
        2 Datatype Appendix F and builds an automata suitable for
         testing strings against that regular expression