title: z3python: converting string to expression
body: <p>Given that <code>x,y,z = Ints('x y z')</code>  and a string like <code>s='x + y + 2*z = 5'</code>,  is there a quick way to convert s into a z3 expression ?   If it's not possible then it seems I have to do lots of string operations to do the conversion.  </p>