| preamble: | |
| property: installedsize: nat = [0], size: nat = [0], sourceversion: string, source: string, number: string | |
| package: a | |
| version: 1 | |
| provides: x=1 | |
| keep: feature | |
| package: a | |
| version: 2 | |
| package: c | |
| version: 1 | |
| depends: foo | |
| package: d | |
| version: 1 | |
| provides: x=1 | |
| request: | |