nl_tokens: Memoizes the createRegexFromDoubleArray with the twoPartTransitionWords .
pl_tokens: function getRegexFromDoubleArray ( twoPartTransitionWords ) { const cacheKey = flattenDeep ( twoPartTransitionWords ) . <mask> ( "" ) ; if ( regexFromDoubleArrayCacheKey !== cacheKey || regexFromDoubleArray === null ) { regexFromDoubleArrayCacheKey = cacheKey ; regexFromDoubleArray = createRegexFromDoubleArray ( twoPartTransitionWords ) ; } return regexFromDoubleArray ; }