code: def copy_subrange_of_file(input_file, file_start, file_end, output_filehandle):
      
      with open(input_file, 'r') as fileHandle:
          fileHandle.seek(file_start)
          data = fileHandle.read(file_end - file_start)
          assert len(data) == file_end - file_start
          output_filehandle.write(data)
docs: Copies the range (in bytes) between fileStart and fileEnd to the given
      output file handle.