Added peek and isEmpty methods to queue + problem on queue

[shoniavika]

Description

Please include a summary of the change and which issue is fixed or what question/feature you have added.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• [x] New feature/question

Checklist:

• [x] My code follows the style guidelines of this project i.e. Pep8
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have squashed unnecessary commits