Extension to fill a VB.NET ComboBox control from a collection or list of strings

FillComboBox.vb

' Requires `Imports System.Runtime.CompilerServices`
Module Extensions
    <Extension()>
    Public Function Fill(Of T)(cb As Control, cc As ICollection(Of T)) As Integer
        Dim cbc As ComboBox = CType(cb, ComboBox)
        Dim n As Integer = 0
        If cc.Count = 0 Then
            Return False
        End If
        For Each cn In cc
            If cbc.Items.Add(cn.ToString) = 1 Then
                n = n = 1
            End If
        Next
        Return n
    End Function

    <Extension()>
    Public Function Fill(cb As Control, first As Integer, last As Integer, stepsize As Integer) As Integer
        Dim cbc As ComboBox = CType(cb, ComboBox)
        Dim n As Integer = 0
        For i As Integer = first To last Step stepsize
            If cbc.Items.Add(i.ToString) = 1 Then
                n = n + 1
            End If
        Next
        Return n
    End Function

    <Extension()>
    Public Function Fill(cb As Control, first As Integer, last As Integer) As Integer
        Dim s As Integer = 1
        If first > last Then
            s = -1
        End If
        Return cb.Fill(first, last, s)
    End Function

    <Extension()>
    Function Fill(cb As Control, last As Integer) As Integer
        Dim s As Integer = 1
        If 0 > last Then
            s = -1
        End If
        Return cb.Fill(0, last, s)
    End Function
End Module