j'ai besoin d'aide en VBA pour écrire une fonction

'Auteur: Alain PROVISTE
Option Base 1 
  
Private Sub AnnaGramme(mot As String, ByRef tablo() As String) 
  
    Dim longueur As Byte 
    Dim i As Byte 
    Dim l As Double 
    Dim k As Byte 
    Dim j As Double 
    Dim motTab() As String * 1 
    Dim annaTab() As String 
    Dim tempmot As String 
    Dim temptab() As String 
    Dim lenTab As Double 
    Dim pos As Double 
    Dim Find As Boolean 
    
    longueur = Len(mot) 
     
    If longueur = 1 Then 
        ReDim tablo(1) 
        tablo(1) = mot 
        Exit Sub 
    End If 
     
    ReDim motTab(longueur) 
     
    For i = 1 To longueur 
         
        motTab(i) = Mid(mot, i, 1) 
         
    Next i 
     
    lenTab = Fac(longueur) 
     
    ReDim annaTab(lenTab) 
     
    For i = 1 To longueur 
         
        tempmot = vbNullString 
         
        Find = False 
         
        For k = 1 To longueur 
            If Find Then 
                tempmot = tempmot & motTab(k) 
            Else 
                If motTab(k) = motTab(i) Then 
                    Find = True 
                Else 
                    tempmot = tempmot & motTab(k) 
                End If 
            End If 
        Next k 
        If Len(tempmot) = 1 Then 
            ReDim temptab(1) 
            temptab(1) = tempmot 
        Else 
            Call AnnaGramme(tempmot, temptab()) 
        End If 
        For j = 1 To lenTab / longueur 
            For l = 1 To UBound(temptab()) 
                annaTab(l + pos) = motTab(i) & temptab(l) 
            Next l 
            DoEvents 
        Next j 
        pos = pos + lenTab / longueur 
    Next i 
    tablo() = annaTab() 
End Sub 
  
Private Function Fac(Number As Byte) As Double 
Dim i As Byte 
Dim a As Double 
    a = 1 
    For i = 1 To Number 
        a = a * i 
    Next i 
    Fac = a 
End Function