check if a excel workbook is open

hi people, today, i discovered this function. it is very usefull, thanks to the authors.

the link to the function is here.
and the function is here:

Function WorkbookOpen(WorkBookName As String) As Boolean
' returns TRUE if the workbook is open
WorkbookOpen = False
On Error GoTo WorkBookNotOpen
If Len(Application.WorkBooks(WorkBookName).Name) > 0 Then
WorkbookOpen = True
Exit Function
End If
WorkBookNotOpen:
End Function

to call this function, use for example:

If Not WorkbookOpen("MyWorkbookName.xls") Then
Workbooks.Open "MyWorkbookName.xls"
End If