1. This question practices the use of a list method. Assign to the variable grades a list of 10 letter grades from among 'A', 'B', 'c','d', and 'F'. For example: grades = ('A', 'F', 'C', 'F', 'A', 'B', 'A', 'C', 'A', 'B'] Write a Python expression that creates a list named frequency, in which the elements are the number of times each of the letters A, B, C, D and F appear in grades. For example, for the above value of grades, the following would be correct output: frequency = [4, 2, 2, 0, 2]