code: def sh (command, as: user, on: hosts, quiet: false, once: nil)
        self.once once, quiet: quiet do
          log.info "sh #{command}", quiet: quiet do
            hash_map(hosts) do |host|
              host.sh command, as: as, quiet: quiet
            end
          end
        end
      end
docs: Execute a shell command on each host
   @macro onable
   @macro asable
   @macro quietable
   @macro onceable