Function explain 

pub fn explain(
    cfg: Option<&Config>,
    base: &Path,
    cwd: &str,
    target: &str,
    full: bool,
) -> Result<Option<Report>, String>

The explanation of target (an argument as typed) from cwd, or None when cwd, the target or the repo they lie in routes off or elsewhere. base is the root store (BORG_HOME). Paths are routed resolved (absolute, symlinks followed), as git sees them.

Errors

A bad line range, a missing file or commit, a file of another collective, or git failing.