`Let` statement

That is some kind of assignment operator. It will always return true, so consider using it in Provided:
Simple example:
```cs
"x provided let x = 4".EvalNumerical()
```
Output:
```cs
4
```

Or more advanced example:
```cs
"x ^ 2 provided let x = 2x - 3".EvalNumerical()
```
Output:
```
9
```

So, do we need it?

No files, tests, or entry points are named. Start by reviewing the existing `Provided` syntax and the examples in the issue, then trace how these expressions are parsed and evaluated. Done requires a maintainer-approved decision on whether `let` belongs in the language, with its behavior and test coverage defined if accepted.

Written by the indexing model from the issue text.