Optimistic Peach questions

Optimistic Peach answers

• How are sized types useful in Rust?
• How to implement fmt::Display on custom type?
• PhantomData type usage in rust
• Why does Rust allow calling functions via null pointers?
• How to create a thread local variable inside of a Rust struct?
• Why can't I import module from different file in same directory? [duplicate]
• How does Box<dyn Trait> deconstruct itself?
• What happens when you clone a `&str`?
• What's the difference between using the return statement and omitting the semicolon in Rust?
• I don't understand the difference between a slice and reference