REPR_A is used for e.g., broadcom build raspberrypi_pi4b.
This is a trick, so that the appended 'f' is attached to the "0.".
Infinity plus zero is still zero, and nan plus zero is still zero.
Without this, a diagnostic occurred:
```
../../extmod/ulab/code/numpy/numpy.c:64:60: error: pasting ")" and "F" does not give a valid preprocessing token
```