code: def next_values(self):
          
  
          nval = []
  
          for k, v in self.children.items():
  
              # if we have reached a value, try to fetch valid completions
              if v['type'] == 'value':
                  if 'complete' in v:
                      nval += v['complete']('')
  
              # otherwise, k is our valid completion
              else:
                  nval.append(k)
  
          return nval
docs: Return list of valid next values