nl_tokens: Replaces characters on specified indices in the input text .
pl_tokens: function replaceCharactersByIndex ( <mask> , indices , substitute ) { const modifiedTextSplitByLetter = text . split ( "" ) ; indices . forEach ( function ( index ) { modifiedTextSplitByLetter . splice ( index , 1 , substitute ) ; } ) ; return modifiedTextSplitByLetter . join ( "" ) ; }