code: def find_available_vc_vers(self):
          
          ms = self.ri.microsoft
          vckeys = (self.ri.vc, self.ri.vc_for_python, self.ri.vs)
          vc_vers = []
          for hkey in self.ri.HKEYS:
              for key in vckeys:
                  try:
                      bkey = winreg.OpenKey(hkey, ms(key), 0, winreg.KEY_READ)
                  except (OSError, IOError):
                      continue
                  subkeys, values, _ = winreg.QueryInfoKey(bkey)
                  for i in range(values):
                      try:
                          ver = float(winreg.EnumValue(bkey, i)[0])
                          if ver not in vc_vers:
                              vc_vers.append(ver)
                      except ValueError:
                          pass
                  for i in range(subkeys):
                      try:
                          ver = float(winreg.EnumKey(bkey, i))
                          if ver not in vc_vers:
                              vc_vers.append(ver)
                      except ValueError:
                          pass
          return sorted(vc_vers)
docs: Find all available Microsoft Visual C++ versions.