Write a program to prompt for a score between 0.0 and 1.0. If the score is out of range, print an error. If the score is between 0.0 and 1.0, print a grade using the following table:

Score Grade
```
>= 0.9 A

>= 0.8 B
>= 0.7 C
>= 0.6 D
< 0.6 F
If the user enters a value out of range, print a suitable error message and exit. For the test, enter a score of 0.85. 
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