ex3.2-1-pre4e.py

s = float(raw_input("Enter a score between 0.0 and 1.0: "))

# give grades for scores in range
# elif skips to end of else:
if s > 0.0 and s < 1.0:
    if s >= 0.9: 
        print "A"
    elif s >= 0.8: 
        print "B"
    elif s >= 0.7: 
        print "C"
    elif s >= 0.6: 
        print "D"
    else: 
        print "F"
        
# if score wasn't in range print error.    
else:
    print "Error: score out of range. Exiting."

actually this is assignment 3.3