Rust_EssentialNoteBook: add Default, Debug trait example.
Rust_EssentialNoteBook: add Default, Debug trait example.

c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet,c86j224s/snippet