Function template 

pub fn template(file_arg: &str) -> FnOptionArg

When editing the commit message, start the editor with the contents in the given file. The commit.template configuration variable is often used to give this option implicitly to the command. This mechanism can be used by projects that want to guide participants with some hints on what to write in the message in what order. If the user exits the editor without editing the message, the commit is aborted. This has no effect when a message is given by other means, e.g. with the -m or -F options. -t , –template=