code: def mv(src, dst):
      
      if not exists(src):
          raise File404(src)
  
      try:
          shutil.move(src, dst)
      except Exception as e:
          raise IOError(str(e))
docs: Move a file or directory.
  
      If the destination already exists, this will attempt to overwrite
      it.
  
      Arguments:
  
          src (string): path to the source file or directory.
          dst (string): path to the destination file or directory.
  
      Raises:
  
          File404: if source does not exist.
          IOError: in case of error.