#I start by putting my if/else statements inside my function
def computegrade(Grade):
  if Grade>=0.9 and Grade<=1.0:
    print("A")
  elif Grade>=0.8 and Grade<=0.89:
    print("B")
  elif Grade>=0.7 and Grade<=0.79:
    print("C")
  elif Grade>=0.6 and Grade<=0.69:
    print("D")
  elif Grade>=0.0 and Grade<=0.6:
    print("F")
  else:
    print ("Bad Score")
  return Grade
# I then set up my loop, which has the function near the top
# I also define the value "Score"
while True:
  Score=int
  if Score=='quit':
    print("Thanks for using the grade calculation program!")
    quit()
  computegrade(Score)
  try:
    Score=float(input("Enter score or type 'quit' to exit: "))
  except:
    print("Bad grade")