# Problem
This is my proposal for fixing #1107 . I've only done it for one stdlib function, `tangentialArcTo` -- if y'all like it, I'll apply this idea to the rest of the stdlib.
Previously, if users want to put a tag on the arc, the function's parameters change type.
```
// Tag missing: first param is array
tangentialArcTo([x, y], %)
// Tag present: first param is object
tangentialArcTo({to: [x, y], tag: "myTag"}, %)
```
# Solution
My proposal in #1006 is that KCL should have optional values. This means we can change the stdlib `tangentialArcTo` function to use them. In this PR, the calls are now like
```
// Tag missing: first param is array
tangentialArcTo([x, y], %)
// Tag present: first param is array still, but we now pass a tag at the end.
tangentialArcTo([x, y], %, "myTag")
```
This adds an "option" type to KCL typesystem, but it's not really revealed to users (no KCL types are revealed to users right now, they write untyped code and only interact with types when they get type errors upon executing programs). Also adds a None type, which is the default case of the Optional enum.
