insert-MRU MRU list function (See related posts)

insert-MRU: func [
    "Insert value in series; removing first existing instance."
    series [series!] 
    value 
    /limit size [integer!] "Limit the series to the given size by removing the last item."
][
    remove find/only series value
    insert/only series value
    if all [size  size < length? series] [remove back tail series]
    series
]