The following is wasteful of vertical space:
```
_ =
let
longIdentifierForShortValue = 1
in
longIdentifierForShortValue + longIdentifierForShortValue
```
We should format it on two lines if possible.
```
_ =
let longIdentifierForShortValue = 1
in longIdentifierForShortValue + longIdentifierForShortValue
```
This commit also allows for a mix of variations:
```
_ =
let
longIdentifierForShortValue = 1
in longIdentifierForShortValue + longIdentifierForShortValue
_ =
let longIdentifierForShortValue = 1
in
longIdentifierForShortValue + longIdentifierForShortValue
```