UnboundLocalError: local variable ' ' referenced before assignment

[buran]

what does "{....:2f} mean? I understand the {dosis:..} fine. thats the one to be used.
When do you use {....:3f or 4f or etc.}

this is string formatting specification
see https://docs.python.org/3/library/string...ing-syntax

.2f means dosis is float number and you want it to be displayed with 2 decimal places precision, e.g.

>>> dosis = 1/3
>>> dosis
0.3333333333333333
>>> f'{dosis:.2f}'
'0.33'
>>> f'{dosis:.4f}'
'0.3333'
>>>