docs: def getFields(self, numTerms=1):
          """Retrieve a list of fields.  The response looks something like:
  {
   'responseHeader':{
      'status':0,
      'QTime':44},
   'index':{
      'numDocs':2000,
      'maxDoc':2000,
      'numTerms':23791,
      'version':1227298371173,
      'optimized':True,
      'current':True,
      'hasDeletions':False,
      'directory':'org.apache.lucene.store.FSDirectory:org.apache.lucene.store.FSDirectory@/Users/vieglais/opt/localsolr_svn/home/data/index',
      'lastModified':'2009-03-12T18:27:59Z'},
   'fields':{
      'created':{
        'type':'date',
        'schema':'I-S----O----l',
        'index':'I-S----O-----',
        'docs':2000,
        'distinct':1,
        'topTerms':['2009-03-12T18:13:22Z',2000],
        'histogram':['2',0,'4',0,'8',0,'16',0,'32',0,'64',0,'128',0,'256',0,
         '512',0,'1024',0,'2048',1]},
      'species_s':{
        'type':'string',
        'schema':'I-SM---O----l',
        'dynamicBase':'*_s',
        'index':'I-S----O-----',
        'docs':1924,
        'distinct':209,
        'topTerms':['cepedianum',352],
        'histogram':['2',34,'4',34,'8',16,'16',13,'32',6,'64',3,'128',1,
         '256',2,'512',2]},
      """
          if self._fields is not None:
              return self._fields
          params = {'numTerms': str(numTerms), 'wt': 'python'}
          request = urllib.parse.urlencode(params, doseq=True)
          rsp = self.doPost(self.solrBase + '/admin/luke', request, self.formheaders)
          data = eval(rsp.read())
          self._fields = data
          return data