[hchasestevens]

Note that this doesn't actually encompass all the possible usages of the PEP-572 operator in the standard library, of which there appear to be 312 more candidates (and a further 100 in the rest of CPython):

  root@8d88e1e678b0:/cpython# astpath -A 1 "//Assign[(targets/Name/@id = following-sibling::*[1][name(.) = 'If']/test/Name/@id)]" > pep-572.txt
  root@8d88e1e678b0:/cpython# grep "Lib" pep-572.txt | head -20
  ./Lib/argparse.py:284   >        help = self._root_section.format_help()
  ./Lib/argparse.py:285            if help:
  ./Lib/argparse.py:2275  >        a = [action for action in positionals
  ./Lib/argparse.py:2276                if action.nargs in [PARSER, REMAINDER]]
  ./Lib/cmd.py:300        >                    doc=getattr(self, 'do_' + arg).__doc__
  ./Lib/cmd.py:301                             if doc:
  ./Lib/cmd.py:356        >        nonstrings = [i for i in range(len(list))
  ./Lib/cmd.py:357                                 if not isinstance(list[i], str)]
  ./Lib/compileall.py:123 >        mo = rx.search(fullname)
  ./Lib/compileall.py:124          if mo:
  ./Lib/dis.py:386        >    show_lineno = linestarts is not None
  ./Lib/dis.py:387             if show_lineno:
  ./Lib/dis.py:403        >        new_source_line = (show_lineno and
  ./Lib/dis.py:404                                    instr.starts_line is not None and
  ./Lib/enum.py:86        >                already = set(value) & set(self._member_names)
  ./Lib/enum.py:87                         if already:
  ./Lib/enum.py:153       >        invalid_names = set(enum_members) & {'mro', }
  ./Lib/enum.py:154                if invalid_names:
  ./Lib/enum.py:848       >    negative = value < 0
  ./Lib/enum.py:849            # issue29167: wrap accesses to _value2member_map_ in a list to avoid race
  root@8d88e1e678b0:/cpython# grep -E "\.py\:[^w]+>" pep-572.txt | wc -l
  412
  root@8d88e1e678b0:/cpython# grep -E "/Lib/.+\.py\:[^w]+>" pep-572.txt | wc -l
  312