title: SymPy: Limit symbol/variable to interval
body: <p>Using SymPy, is it possible to limit the possible values of a symbol/variable to a certain range? I now I can set some properties while defining symbols, like <code>positive=True</code>, but I need more control, i.e. I need to set it to be in the interval [0,1]. This assumption should then be used for solving, simplifying etc.</p>