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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 parse_config(config_file=None):
    '''
    Returns a dict of poudriere main configuration definitions

    CLI Example:

    .. code-block:: bash

        salt '*' poudriere.parse_config
    '''
    if config_file is None:
        config_file = _config_file()
    ret = {}
    if _check_config_exists(config_file):
        with salt.utils.files.fopen(config_file) as ifile:
            for line in ifile:
                key, val = salt.utils.stringutils.to_unicode(line).split('=')
                ret[key] = val
        return ret

    return 'Could not find {0} on file system'.format(config_file)