Docstrings should be forced to use triple quotes

[dougthor42]

Operating system: Windows 10 Pro 1809 + WSL (Ubuntu 18.04.2 LTS) Python version: 3.6.7 Black version: 19.0b3 Does also happen on master: yes (via online formatter)

Related: #144.

Even if #144 is not implemented, Black should update docstrings to be triple double quotes.

def foo():
    "Hello"
    pass

# formats to:
def foo():
    """Hello"""
    pass

Thoughts?

[ambv]

This is indeed what PEP 257 is suggesting. My only concern is what happens if this pushes the docstring over the line (e.g. makes it too long).

In any case, we will be deciding what to do about it as part of #144. Thanks!

[graingert]

@ambv can we re-open this? it looks like it wasn't addressed as part of https://github.com/psf/black/issues/144#issuecomment-628137144