>>> check_output(['ls'], input=None, encoding='utf-8')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/ak/opensource/cpython4/Lib/subprocess.py", line 466, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ak/opensource/cpython4/Lib/subprocess.py", line 549, in run
    stdout, stderr = process.communicate(input, timeout=timeout)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ak/opensource/cpython4/Lib/subprocess.py", line 1206, in communicate
    stdout, stderr = self._communicate(input, endtime, timeout)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ak/opensource/cpython4/Lib/subprocess.py", line 2035, in _communicate
    self._save_input(input)
  File "/Users/ak/opensource/cpython4/Lib/subprocess.py", line 2115, in _save_input
    self._input = self._input.encode(self.stdin.encoding,
                  ^^^^^^^^^^^^^^^^^^
AttributeError: 'bytes' object has no attribute 'encode'. Did you mean: 'decode'?