anchor.diff:    [ stock1 (TimeSpan(0, 1, 0)) 1000 |> Chart.FastLine
       stock2 (TimeSpan(0, 1, 0)) 1000 |> Chart.FastLine ]
   (**
  -The above snippet generates 1k of prices in one minutte intervals and plots them using the
  +The above snippet generates 1k of prices in one minute intervals and plots them using the
   [F# Charting library](https://github.com/fsharp/FSharp.Charting). When you run the code
   and tweak the chart look, you should see something like this:
   
  
positive.code: (default value used in the previous example), the function uses the last key
  of the window as the key of the aggregated value. When you specify 
  `Boundary.AtEnding`, the last key is used, so the values can be nicely 
  aligned wiht original values. When you want to specify custom key selector,
  you can use a more general function `Series.aggregate`. 
  
  In the previous sample, the code that performs aggregation is no longer
  
negative.code: as the key (here, we use `DateTimeOffset`, but any type of date will do), we can combine
  multiple series and align them automatically to specified date keys.
  
  To demonstrate this feature, we generate random prices in 60 minute, 30 minute and 
  65 minute intervals:
  *)
  
  