Write a script $($Ch$5/$P$15.$py$)$ that ask the user to enter five test scores. The script should display a letter grade for each score and the average test score. Write the following functions in the script:

cal$\_$average. This function should accept five test scores as arguments and return the average of the scores.

cal$\_$grade. This function should accept a test score as an argument and return a letter grade for the score based on the following grading scale:

Score Letter Grade

$90-100$ A

$80-89$ B

$70-79$ C

$60-69$ D

Below $60$ F

Create Ch$5/$P$15.$py