`round` fails when encountering a `Single`

[mickp]

>>> round(1.23)
1
>>> round(System.Double(1.23))
1
>>> round(System.Numerics.BigInteger(123))
123
>>> round(System.Single(1.23))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: type Single doesn't define __round__ method

[mickp]

Is SingleOps incomplete?

[slozier]

Is SingleOps incomplete?

Indeed, it looks like __round__ was never implemented on SingleOps. It's also not on DecimalOps and other integral types (you could argue that since it works on System.Int32 then why not System.Int16 and friends?).