Function plan 

pub fn plan(
    cli: &Cli,
    config: &Config,
    cwd: &Path,
    clock: &dyn Clock,
) -> Result<Plan, ResolveError>

Resolves arguments, the working directory and the clock into a Plan.

Precedence for each value is: explicit argument, then whatever the working directory reveals through the configured template, then a date-based default.

Errors

Returns ResolveError::LanguageRequired if the mode needs a language and none could be determined, or ResolveError::Template if the template’s matcher cannot be compiled.