Your company wants you to develop a simple OO Python command line $($i$.$e$.,$ non$-$GUI$)$ app to allow employees to maintain their own contact lists. This app is intended to be used by one single user and his$/$her contact lists are not sharable with any other employees.

Use this app, an employee can maintain one or more contact lists, each list has a unique name, which must contain no spaces and is assigned by the employee. Every contact is limited to appear in one and only one contact list and must contain three data in the order of name $($of a person or organization and may be multi$-$word$),$ phone $($any format$),$ and email $($any format$).$

There is no size limit on each contact list, i$.$e$.,$ a list could be empty or contain many contacts.

All contact lists of the user$/$employee must be saved together in one single text file named contacts.txt in a format and organization of your selection. This file, if exists, is assumed to be saved in the same place as where the app is located.

It is also assumed that there is no confidential data in the contact lists and, therefore, no login or any security controls are needed to run the app.$$

User can use the app to select one of the contact lists in the file, add a new contact list to the file, or remove one $($empty or not$)$ from the file.

For a contact list that is specified by the user and is found in the file, the app can help to display the whole list of contacts, or search, add, delete, update a specific contact in the list. Once is done, the app should allow user to use the same list to perform more operations, or switch to another contact list.

Before this app is implemented and tested in Question $7(30$ points$),$ you are required to work through one iteration of SDLC from Question $1$ to $6$ to define and analyze the app's functional requirements, design necessary classes, file, and interfaces, etc. To document your analysis and design results, you need to create and submit different UML diagrams as specified by each question from $1$ to $6.$ Either you draw these diagrams by hand or using a tool, you should save each diagram as an image file and use the Insert $>$ Image $>$ Upload Image menu of the text entry box to insert the file to complete each problem.

Question $1$

Create one$$package diagram$$to specify the layered architecture of the app$$described above. Also, add Note notations in your diagram to describe what each package contains.$$

Question $2$

Create one$$use case diagram$$to specify the overall functional requirements of the app described above. It should contains actor$($s$),$ use case$($s$),$ and system boundary. For the exam purpose, your diagram is expected to also contain$<>$and$<>$relationships$.$

Use cases should be named properly to clearly indicate$$what it performs$$or$$what it interacts with actors.

Question $3$

Create one$$activity diagram$$to document the flow within a use case$$of your selection. That is$,$ you may select any use case that appears in the use case diagram you created in the previous problem. This diagram must contain$$partitions$,$start$$and$$stop$$activities$.*$Note that this activity diagram will serve as a design base for a sequence diagram to solve Problem $5.$

Question $4$

Create one$$class diagram$$to document business$-$level classes that model entities and their relationships of the app's business domain. This diagram must contain all classes in the entire problem space of the app, not just one$$ or a few use cases of the app.

$*$Note that another class diagram at the design level will be created next to include technical classes in the solution space.

Question $5$

Based on the activity diagram you completed in Problem $3,$ create one$$design$-$level sequence diagram$$to model the detailed interactions between various types of objects $($e$.$g$.,$boundary$,$ control, entity, container, file, etc.$)$in the solution space. Every interaction in the diagram must be represented by an object's$$message$$and there should be only$$objects$$and no longer actors exist in the diagram.

Question $6$

Based on the analysis$-$level class diagram and sequence diagram you completed in the previous two probelms, create a$$design$-$level$$class diagram$$to incorporate technical classes in the solution space, including a boundary class, control classes, entity classes, a container or collection class $($for lists of contacts$),$ and a $<>$ stereotyped class.