Function long_help 

pub fn long_help(
    spec: &Spec<'_>,
    path: &[&str],
    chain: &[&CommandMeta<'_>],
) -> String

Everything --help prints.

The same content as short_help through a wider layout: help is aligned into a column and wrapped, the long form of each description is preferred over the short one, and the annotations — choices, environment, default — each get their own line.

An entry whose help contains a line break is laid out as a block instead, its text indented under the usage rather than beside it, because there is no column that keeps a line the author already broke readable.