https://docs.python.org/3/library/urllib.parse.html

1. It's my understanding that the arguement in the displayed usage shows the default. So:
   urllib.parse.quote(string, safe='/', encoding=None, errors=None)
   means that errors defaults to NoneType, however, the documentation just below that says:

"errors defaults to 'strict'

2. quote: There isn't a list of possible values for the "errors" argument

3. unquote - There isn't a list of possible values for the "errors" argument

4. unquote -

errors defaults to 'replace', meaning invalid sequences are replaced by a placeholder character.

What "placeholder character" is it that's used?

5. unquote

encoding defaults to 'utf-8'. errors defaults to 'replace', meaning invalid sequences are replaced by a placeholder character.

Is a single line. errors should be on a new line (all arguements for all functions really should always be on a new line unless there's a compelling reason not to. To do otherwise significantly impedes readability, while increasing the chances of misunderstanding).