[IronPython] Passing a reference to a string

[John Barham]

I'm trying to call a C# method from IP that takes a reference to a
string as one of its parameters.  I'm passing it a System.String()
object, but the string is not changed after I call the method.  I know
that CPython (and presumably IP) strings are immutable so how do I get
C# to change the string object that I pass in?

Thanks,

  John