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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _upstart_disable(name):
    '''
    Disable an Upstart service.
    '''
    if _upstart_is_disabled(name):
        return _upstart_is_disabled(name)
    override = '/etc/init/{0}.override'.format(name)
    with salt.utils.files.fopen(override, 'a') as ofile:
        ofile.write(salt.utils.stringutils.to_str('manual\n'))
    return _upstart_is_disabled(name)