lib/renderer.js
function checkValue(config, res, key, trueVal, falseVal) {
    res[key] = (config[key] == true || config[key] == undefined || config[key] == null) ? trueVal: falseVal;
}
function checkValue(config, res, key, trueVal, falseVal) {
    res[key] = (config[key] == true || config[key] == undefined || config[key] == null) ? trueVal: falseVal;
}
function checkValue ( config , res , key , trueVal , falseVal ) { res [ key ] = ( config [ key ] == true || config [ key ] == undefined || config [ key ] == null ) ? trueVal : falseVal ; }
General Default markdown-it config.
@param  {Object} config configuration
@param  {Object} res    configuration
@param  {String} key    the key of config
@param  {String} trueVal    the val of config[key] == true
@param  {String} falseVal    the val of config[key] == false
@return {null}
General Default markdown - it config .