When global and local varible  in the same name.
the local varibale in a mehod or function which use to 
override the global is called the shadowing.
ie the Global varible is being shadowed by the 
local varible

If there are overloaded methods in the base class, & u 
marks one of the methods as shadows using the keyword 
shadow in the derived class, then we cannot access the 
overloaded methods.

Ex-
public class base
  public sub test()
console.writeline("sonia")
 end sub

public sub test(i as integer)
 console.writeline(i)
end sub

end class

public sub derived
inherirts base
 shadows sub test(x as integer)
console.writeline("Shadow method")
end sub
end class


sub main()
dim obj as new derived
obj.test()-->Invalid
obj.test(10)-->Valid
end sub

Whatever the code written by Sonia.sardana is shows the 
shadowing concept but there is some print mistakes in the 
code.The correct code is---


imports system
module m1 
public class base
 Public Sub test()
        Console.WriteLine("sonia")
    End Sub

    Public Sub test(ByVal i As Integer)
        Console.WriteLine(i)
    End Sub

End Class

Public class derived
    inherits base

Shadows Sub test(ByVal x As Integer)
    Console.WriteLine("Shadow method")
End Sub
end class


Sub main()
    Dim obj As New derived
obj.test()  'This will show error
obj.test(10) 'This is valid
End Sub
    
end module