nl_tokens: apply a function to all values should only be used for side effects ( fn ) - > prom
pl_tokens: function each ( fn ) { assert . equal ( typeof fn , 'function' ) return function ( arr ) { arr = <mask> . isArray ( arr ) ? arr : [ arr ] return arr . reduce ( function ( prev , curr , i ) { return prev . then ( function ( ) { return fn ( curr , i , arr . length ) } ) } , Promise . resolve ( ) ) . then ( function ( ) { return arr } ) } }