Table.PreviousRow.pq

let func =   
 (MyTable as table, MyColumnName as text) =>
let
    Source = MyTable,
    ShiftedList = {null} &  List.RemoveLastN(Table.Column(Source, MyColumnName),1),
    Custom1 = Table.ToColumns(Source) & {ShiftedList},
    Custom2 = Table.FromColumns(Custom1, Table.ColumnNames(Source) & {"Previous Row"})
in
    Custom2 ,
documentation = [
Documentation.Name =  " Table.PreviousRow ",
Documentation.Description = " Superfast way to reference previous row ",
Documentation.LongDescription = " Superfast way to reference previous row ",
Documentation.Category = " Table ",
Documentation.Source = " www.TheBIccountant.com .  http://tiny.cc/hhus5y . ",
Documentation.Version = " 1.0 ",
Documentation.Author = " Imke Feldmann: www.TheBIccountant.com. http://tiny.cc/hhus5y . ",
Documentation.Examples = {[Description =  "  ",
Code = "  ",
Result = "  "]}]
  
 in  
  Value.ReplaceType(func, Value.ReplaceMetadata(Value.Type(func), documentation))