Start numbering from value other than 1

**Is your feature request related to a problem? Please describe.**
In some cases, I would like to be able to specify that numbering starts from a custom value, other than `1`.

**Describe the solution you'd like**
Ability to specify an _offset_ which should be used for particular `code` block.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A
