Module CurrencyFormatting
    Public Function Currency(amount As Double, width As Integer, Optional minus As String = "-") As String
        ' Ensure width and minus parameters are valid
        If width <= 0 OrElse minus Is Nothing OrElse String.IsNullOrEmpty(minus) Then
            Throw New ArgumentException("width must be a positive integer and minus a non-empty string")
        End If

        ' Convert amount to a double
        Dim sign As String
        Try
            amount = CDbl(amount)
        Catch ex As InvalidCastException
            Throw New InvalidCastException("amount must be a valid number", ex)
        End Try

        ' Determine the sign of the amount
        If amount < 0 Then
            sign = minus
            amount = -amount
        Else
            sign = New String(" "c, minus.Length)
        End If

        ' Format the amount with two decimal places
        Dim amountStr As String = Math.Abs(amount).ToString("F2")

        ' If the formatted amount is less than the width, pad with spaces to the left
        If amountStr.Length < width Then
            amountStr = New String(" "c, width - amountStr.Length) + amountStr
        End If

        ' Format as currency
        Dim currencyStr As String = "$" + amountStr + sign
        Return currencyStr
    End Function

    Sub Main()
        ' Example calls to the currency formatting function
        Dim formattedAmount1 As String = Currency(123.456, 10)
        Dim formattedAmount2 As String = Currency(-78.9, 12, "NEG")
        Dim formattedAmount3 As String = Currency(0, 8)

        ' Output the results
        Console.WriteLine(formattedAmount1) ' Output: $   123.46
        Console.WriteLine(formattedAmount2) ' Output: $   78.90NEG
        Console.WriteLine(formattedAmount3) ' Output: $   0.00 

        ' Wait for user input before closing
        Console.WriteLine("Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module