# from https://github.com/danhper/fish-ssh-agent/
function __ssh_agent_is_started -d "check if ssh agent is already started"
        if begin; test -f $SSH_ENV; and test -z "$SSH_AGENT_PID"; end
                source $SSH_ENV > /dev/null
        end

        if begin; test -z "$SSH_AGENT_PID"; and test -z "$SSH_CONNECTION"; end
                return 1
        end

        ssh-add -l > /dev/null 2>&1
        if test $status -eq 2
                return 1
        end
end