How to define a byte string in python

"
o = bytes ("helloworld","utf-8")
r = o.center
print (r)

"

the second line of python code above reported an error. The error prompt is as follows:
r = o.center
TypeError: center () argument 2 must be a byte string of length 1, not str

The

error indicates that the second parameter of the center () method must be a byte string of length 1.
there is no great god until how to define a byte string in python.

Mar.24,2021

it's strange why you can't delete your own questions. So I had to answer my own questions. No, no, no.
o = bytes ('helloworld','utf-8')
fill = bytes (' -', 'utf-8')
r = o.center
print (r)

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e591af-454f6.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e591af-454f6.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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