Function key_name 

pub fn key_name<A: ActionSet>(keys: HelpKeys<'_, A>, action: A) -> String

The name of the key for action (its Keymap::primary chord), e.g. f or Shift+Space; on a controller, of its button or button chord (Keymap::primary_button) as that pad labels it, e.g. A or A+B. HelpKeys::not_mapped if it has none.