nl_tokens: Add API feature item . Return the feature item to add or return false if existed .
pl_tokens: function addFeatureItem ( logger , existed , name , params ) { if ( ! existed [ name ] ) { existed [ name ] = true ; let feature = { name } ; params && ( feature . params = params ) ; return feature ; } logger . debug ( 'duplicated feature declaration' , name ) ; return <mask> ; }