Set the header in urllib.request python 3

问题

What is the meaning of body (refers to?) in the code below?

headers = ['Content-length']=str(len(bytes(body, 'utf-8')))

return urllib.request.Request(theurl, bytes(body, 'utf-8'), headers)

Sourse : BadStatusLine exception raised when returning reply from server in Python 3

来源：https://stackoverflow.com/questions/38418477/set-the-header-in-urllib-request-python-3