Question

In some karate dojo (schools), you can tell the level of a student by the colour of their obi (belt). 

In this assignment, you will write a function that will reverse the student records in a dojo such that the key is the belt and the value is a list of students that have attained that belt level. 

Write a function:

dojo_reversal(entries)

which consumes a dictionary where the key is the student's first name and the value is the colour of their belt. The function should return the reversed dictionary so that the key is the belt colour and the value is a list of all students in alphabetical order who have attained that belt level.

Note: You can assume that the belt colour will always be lowercase, latin letters.

Examples:

dojo_reversal({}) => {}

entries = {'Daniel': 'blue', 'Demetri': 'yellow', 'Dusten': 'white',
           'Hawk': 'blue', 'Samantha': 'blue', 'Johnny': 'brown',
           'Miguel': 'green', 'Robby': 'green'}
dojo_reversal(entries) => {'blue': ['Daniel', 'Hawk', 'Samantha'],
                           'brown': ['Johnny'], 
                           'green': ['Miguel', 'Robby'], 
                           'white': ['Dusten'], 
                           'yellow': ['Demetri']}