Function us_concat 

pub fn us_concat<C: Cost>(xs: impl IntoIterator<Item = Doc<C>>) -> Doc<C>

Concatenates several documents horizontally with spacing.

Equivalent to calling us_append successively to combine the documents in the iterator. If the iterator is empty, it returns text("").

Example

let doc = us_concat([text("hello"), text("world")]);
assert_eq!(doc.to_string(), "hello world");

let doc = us_concat([]);
assert_eq!(doc.to_string(), "");