Module CheckStack {
      \\ ordered collection: Stack
      \\ we can add values to top or bottom,
      \\ we can move values to and from top
      A=Stack:=100,300,600,800,900
      Print StackItem(A, 2)=300, Len(A)=5
      Stack A {
            \\ push to bottom (or end)
            Data 2000, 4000
      }
      Print StackItem(A, 7)=4000, Len(A)=7
      Stack A {
            \\ pop from top
            Read X, Y
            Print X=100, Y=300
      }
      Print StackItem(A,5)=4000, Len(A)=5
      Stack A {
            \\ push to top
            Push 2, 1
            Stack    ' display stack items
      }
      \\ we can make a new stack merging other stacks
      A=Stack(A, stack:=5000,6000,7000)
      Print Len(A)=10
      Stack A {
            Shift 1,-Len(A)  ' Reverse order
            Stack ' Display
      }
      Stack A {Drop 8}
      Print Len(A)=2
      Flush  ' empty current stack
      Stack A  ' dump A to current stack
      Print Stack.Size=2, Len(A)=0
}
CheckStack