Fixed LinkedList:

[yossan]

Checklist

• [*] I've looked at the contribution guidelines.
• [*] This pull request is complete and ready for review.

• I am confirming that this pull request can merge #583 Linked list conformance to collection protocol and pass the test.

Description

• Modified node(atIndex:) method not to return nil, and code refactoring.
• Deleted nodesBeforeAndAfter(index:) method, and modified insert methods.
• Modified readme file.

[hollance]

How about 'guard var node = head { ... }'. This saves having to write 'var node = head' below the guard statement.

[yossan]

Thanks for your suggestion.
I adopted it.
dc810d2

[yossan]

I apologize for having sent a lot of commits after pull request.
I would be grateful if you would review this pull request.

[kelvinlauKL]

Nice changes overall. I left a comment at one of the many signatures with the following style:

node(atIndex:)

Changing it to node(at index: Int) would read nicer at the call site: node(at: 10), and fits in better with the ones in the collection apis.

[kelvinlauKL]

node(at index: Int) would read a bit more like the other collection apis.

[yossan]

Thank you for your review.
I renamed atIndex to at by the following methods:

• node(atIndex:)
• insert(_:, atIndex:)
• remove(atIndex:)

bb21f61

[kelvinlauKL]

Good changes!

[kelvinlauKL]

Thank you @ysn551!