x
x
x


Do so in a way which:

 does not involve string manipulation of the input source code
 is plausibly extensible to a runtime-chosen set of bindings rather than just x
 does not make x a global variable


or note that these are impossible.



See also

 For more general examples and language-specific details, see Eval.
 Dynamic variable names is a similar task.


>>> def eval_with_x(code, a, b):
	return eval(code, {'x':b}) - eval(code, {'x':a})
 
>>> eval_with_x('2 ** x', 3, 5)
24