Hello!

I've found some strange thing: If I have an expression with square root in it, and try to substitute it, like

```
Eq := \sqrt(X);
substitute(Eq, $\sqrt(X) -> A$);
```

it works and I get A. But if I send it to sympy in the middle, the substitution stops working

```
Eq := \sqrt(X);
map_sympy(Eq, 'simplify');
substitute(Eq, $\sqrt(X) -> A$);
```

This particular example is silly, but it illustrates the problem.