6. Signum Libri (SL) is a publishing company. Create the ER diagram for the SL Operations Database based on the following requirements. SL Operations Database will keep track of the following: For each book SL publishes: a book name, genre, date of publication, and number of pages For each writer: a unique writer identifier as well as the writer's name For each agent: a unique agent identifier as well as the agent's name For each editor: a unique editor identifier as well as the editor's name Each SL book is written by one writer, and each writer can write many SL books. SL will not keep track of writers who did not write a book for SL. All books written by the same writer have a different book name. However, two writers can write two different books with the same book name. Each writer is represented by one agent. Each agent represents at least one writer but can represent many. Each book has one editor. Each editor edits at least one book but can edit many books. Each editor can mentor one or more other editors but does not have to mentor any. Each editor can have at most one mentor editor but does not have to have any