`i_CTRL-O` may change the cursor position in an unexpected way.
For example, when `autoindent` is set, the user will expect that
`i asdf<CR><C-O>` will place the cursor right below `a`.
However, `<C-O>` moves the cursor to the first column of line 2.
Expected:
```
asdf
█
```
Actual:
```
asdf
█
```
Therefore, it's desirable to use `i_CTRL-\_CTRL-O`, the variant of
`i_CTRL-O` that does not move the cursor.
