> So := is 'gets a truthy value from'?

No, “if <expression>” expands to “if <expression> has a truthy value”.

“<var> := <expression>” is itself an expression, which can be best (IMO) read in English as “<var> (which is <expression>)”

How about "assigns to and returns"?

we added new syntax for a code pattern that has inherent complexity which can't be reduced.

It can be reduced into two simpler lines can’t it, both of which could be understood in isolation.

understanding lines in isolation is precisely besides the point here, because the code pattern has to be understood as a whole.

I don’t see why. ‘Assign x’ and ‘is x truthy’ can be understood separately. Worry about what x is being assigned. Then worry about whether its value is truthy.

like I said, the whole pattern is more than two lines. the pattern is actually assign-test-fallback-test-fallback-test-etc.

to quote the PEP:

  reductor = dispatch_table.get(cls)
  if reductor:
      rv = reductor(x)
  else:
      reductor = getattr(x, "__reduce_ex__", None)
      if reductor:
          rv = reductor(4)
      else:
          reductor = getattr(x, "__reduce__", None)
          if reductor:
              rv = reductor()
          else:
              raise Error(
                  "un(deep)copyable object of type %s" % cls)

becomes:

  if reductor := dispatch_table.get(cls):
      rv = reductor(x)
  elif reductor := getattr(x, "__reduce_ex__", None):
      rv = reductor(4)
  elif reductor := getattr(x, "__reduce__", None):
      rv = reductor()
  else:
      raise Error("un(deep)copyable object of type %s" % cls)