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New checks:
* E225: require whitespace around ``and`` ``in`` ``is`` and ``or``. PR 847.
Changes:
* E117: fix indentation using tabs by treating as 8-space indents. PR 837.
* E721: fix false positive with names containg ``istype``. PR 850.
* E741: allow ``l`` as a named argument in a function call. PR 853.
* E302: fix false-negative with decorated functions. PR 859.
* W504: ellipsis (``...``) is no longer treated as a binary operator. PR 875.
* E402: allow ``with``, ``if``, ``elif``, ``else`` to guard imports. PR 834.
* Add support for assignment expressions ``:=`` (PEP 572). PR 879.
* Add support for positional-only arguments ``/`` (PEP 570). PR 872, 918.
* Add support for python 3.8.
* Add support for matrix multiplication operator ` (PEP 465). PR 897.
* Support visual indent for continuation lines for ``with`` / ``assert`` /
``raise``. PR 912.
* E302: allow two blank lines after a block of one-liners. PR 913.
* E302: allow two-and-fewer newlines at the top of the file. PR 919.