old_contents: # Tai Sakuma <sakuma@fnal.gov>
  
  ##____________________________________________________________________________||
  class WritePandasDataFrameToFile(object):
      def __init__(self, outPath):
          self._outPath = outPath
  
      def deliver(self, results):
          if len(results.index) == 0: return
          f = open(self._outPath, 'w')
          results.to_string(f, index = False)
          f.close()
  
  ##____________________________________________________________________________||
  
new_contents: # Tai Sakuma <sakuma@fnal.gov>
  
  ##____________________________________________________________________________||
  class WritePandasDataFrameToFile(object):
      def __init__(self, outPath):
          self._outPath = outPath
  
      def deliver(self, results):
          f = open(self._outPath, 'w')
          if len(results.index) == 0:
              f.write(" ".join([i for i in results.columns]) + "\n")
          else:
              results.to_string(f, index = False)
          f.close()
  
  ##____________________________________________________________________________||
  
subject: write the output file when the DaraFrame is empty