code: def _open_target_files(self):
          '''
          Checks if the target files can be opened.
          Any files that cannot be opened are removed from the self.target_files list.
          '''
          # Validate the target files listed in target_files
          for tfile in self.files:
              # Ignore directories.
              if not self.subclass == io.FileIO or not os.path.isdir(tfile):
                  # Make sure we can open the target files
                  try:
                      fp = self.open_file(tfile)
                      fp.close()
                      self.target_files.append(tfile)
                  except KeyboardInterrupt as e:
                      raise e
                  except Exception as e:
                      self.error(description="Cannot open file %s (CWD: %s) : %s" % (tfile, os.getcwd(), str(e))f _open_target_files(self):
          '''
          Checks if the target files can be opened.
          Any files that cannot be opened are removed from the self.target_files list.
          '''
          # Validate the target files listed in target_files
          for tfile in self.files:
              # Ignore directories.
              if not self.subclass == io.FileIO or not os.path.isdir(tfile):
                  # Make sure we can open the target files
                  try:
                      fp = self.open_file(tfile)
                      fp.close()
                      self.target_files.append(tfile)
                  except KeyboardInterrupt as e:
                      raise e
                  except Exception as e:
                      self.error(description="Cannot open file %s (CWD: %s) : %s" % (tfile, os.getcwd(), str(e)))
docs: Checks if the target files can be opened.
          Any files that cannot be opened are removed from the self.target_files list.