Stage 7.13: Formatting Strings
The format! macro allows us to create a string by defining a parameterized string
with placeholders for where and how values should be placed, e. g. {}).
format! uses the same parameterized strings as println!
To print arrays, structs, enums etc. you simple add :? to the curly brackets, e. g.
{:?}
You can also use a pretty-print by adding :#? to the curly brackets, e. g.
{:#?}
Further information: