If I try to use collect_factors for an expression that contains exponents, it does not collect them into one exponent, for example:

`collect_factors($\exp(-2\sigma-2\kappa) \exp(2\sigma) \exp(2\kappa)$);`

these exponents can only be removed by map_sympy(ex, "simplify"), but it can't be used with zoom function, for example. same situation with product_rule.