Bug report regarding string.replace() inside a formatter line

[rmetrich]

Hi,
I've started using micropython on a esp8266, it's just great!
I would like to report a bug in string's replace() implementation with colon replacement.
I could confirm it also fails with the online unicorn emulator, please find below the code excerpt:

>>> temps = dict()
>>> temps['a'] = "20.5:1"
>>> "&".join(map(lambda i: f"{i[0]}={i[1].replace(':', 'foo')}", temps.items()))
Traceback (most recent call last):
  File "<stdin>", line 1
SyntaxError: invalid syntax

This kind of code works find on regular python.
It seems to be an issue only when using a f"" formatter.

[scruss]

There are a lot of f-string features that MicroPython doesn't support: MicroPython differences from CPython | Core language.

There must be a less convoluted way of expressing this code.

[mendenm]

One of the specifically unavailable features is object indexing inside an f-string.