code: def merge(filehandle_1, filehandle_2, output_filehandle):
      
      line2 = filehandle_2.readline()
      for line1 in filehandle_1.readlines():
          while line2 != '' and line2 <= line1:
              output_filehandle.write(line2)
              line2 = filehandle_2.readline()
          output_filehandle.write(line1)
      while line2 != '':
          output_filehandle.write(line2)
          line2 = filehandle_2.readline()
docs: Merges together two files maintaining sorted order.