Filter list of voltage levels with depth

[flo-dup]

Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines
• [x] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

Does this PR already have an issue describing the problem ? No

What kind of change does this PR introduce? Feature

What is the new behavior (if this is a feature change)? Generating the SVG of part of the network, given a list of voltage levels and a unique depth

Does this PR introduce a breaking change or deprecate an API? No