请高手帮我把这段vb代码转换成c#代码？

Private Function LShift(lValue, iShiftBits)
If iShiftBits = 0 Then
LShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And 1 Then
LShift = &H80000000
Else
LShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If

If (lValue And m_l2Power(31 - iShiftBits)) Then
LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000
Else
LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits))
End If
End Function

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-- line 1 col 9: invalid NonModuleDeclaration

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第一句似乎有错误 Private Function LShift(lValue, iShiftBits)

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没有人会吗？

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函数VB code:
Private Function LShift(lValue, iShiftBits)
为什么没有返回值呢