Function run 

pub fn run(
    package_name: &str,
    upstream: bool,
    raw: bool,
    page: Option<&str>,
) -> Result<()>

Runs the manual page viewer for the specified package.

Without --page, the page matching the package name in section 1 (<name>.1) is shown. Pass --raw to print the raw page source to stdout instead of opening a viewer.

Errors

Returns an error if:

• The package cannot be resolved.
• No manual pages can be found, or the requested --page does not exist.
• The selected viewer fails.