User input only takes the last number

[Austin11]

I changed up my code to take away the extra while loop and include it in the first while statement when the user puts in a negative it works great. However, when they put in a string I receive a ValueError like below. I have a feeling it has to do with my is_actual_float function but I can't seem to figure out where. I tried changing things around but it didn't work.

Traceback (most recent call last):
  File "C:/Users/Eman/Desktop/lab5_2/lab5.py", line 82, in <module>
    main()
  File "C:/Users/Eman/Desktop/lab5_2/lab5.py", line 75, in main
    pints_collected = get_pints_for_drive()
  File "C:/Users/Eman/Desktop/lab5_2/lab5.py", line 24, in get_pints_for_drive
    pints = float(input("Enter pints collected: "))
ValueError: could not convert string to float: 'Im lost'

Also, I tried your second recommendation with the max and min and for some reason, I keep getting an error message whether it be the format you gave me or the python shortcuts. I know your format is correct along with the python shortcuts. In short, I just need a quick explanation of what the following error message means. I've looked on the internet and just cannot find a concrete answer.

Traceback (most recent call last):
  File "C:/Users/Eman/Desktop/lab5_2/lab5.py", line 82, in <module>
    main()
  File "C:/Users/Eman/Desktop/lab5_2/lab5.py", line 77, in main
    maximum = max(pints_collected)
TypeError: 'float' object is not iterable