## foo
### foo
### foo 1
## foo 1
## foo 2
### foo
#### 4th level headings
All 4th level headings should not be shown by default

## bar
### bar
#### bar
4th level heading should be ignored by default, but is should be always taken
into account, when generating slugs
### `bar`
#### `bar`
## bar
### bar
#### bar
## bar
