Urgent help needed in Python ! Thanx :)

# Create an empty list of grades. # Prompt the user to enter a single grade. # 1) Repeatedly prompt the user to enter a grade with the prompt 'Grade? ' # until the user enters a grade less than 0. Add each of these grades to the # grades list. Do not add the grade that is less than 0 to the list of grades. # 2) Print the number of grades that are the 'B' range. The 'B' range is # defined as greater than or equal to 80 and less than 90. # 3) Print the maximum grade in grades. # 4) Replace all grades that are less than 65 in the grades list with 65. # For example, if there is a grade of 50, it should be replaced with 65. # 5) Print out the average of all grades. To calculate the average, # you must add up all of the grades and divide by the number of grades.