Return True if current user is a sudoer, else False.

    Should be called non-eager if sudo is wanted only.

def _is_sudoer(what_for=''):
    '''Return True if current user is a sudoer, else False.

    Should be called non-eager if sudo is wanted only.
    '''
    if env.get('nosudo', None) is None:
        if what_for:
            print(yellow(what_for))
        with quiet():
            # possible outputs:
            #  en: "Sorry, user winhost-tester may not run sudo on <hostname>"
            #  en: "sudo: a password is required"     (=> is sudoer)
            #  de: "sudo: Ein Passwort ist notwendig" (=> is sudoer)
            output = run('sudo -nv', capture=True)
            env.nosudo = not (output.startswith('sudo: ') or output == '')
        if env.nosudo:
            print('Cannot execute sudo-commands')
    return not env.nosudo