Why do designers use tonal shading?

Jason works as an accountant in a department store. he needs to keep a daily record of all the invoices issued by the store. which file naming convention would him the most? a)give the file a unique name b)name the file in yymmdd format c)use descriptive name while naming the files d)use capital letters while naming the file

Technician a says that with self-adjusting clutch systems, the release bearing constantly rotates. technician b says that the ball bearing portion of the release bearing should be lubricated with high-temperature grease during routine maintenance. which technician is correct?

Description: write function lastfirst() that takes one argument—a list of strings of the format "lastname, firstname" —and returns a list consisting of two lists: (a) a list of all the last names (b) a list of all the first names