SSH into the server(s) (sequentially if more than one)

    Args:
        cmd (str) ='': Command to run on the server

def ssh(cmd=''):
    '''
    SSH into the server(s) (sequentially if more than one)

    Args:
        cmd (str) ='': Command to run on the server
    '''
    with settings(warn_only=True):
        local('ssh -A -o StrictHostKeyChecking=no -i "%s" %s@%s "%s"' % (
            env.key_filename, env.user, env.host, cmd))