## Naming
Abbreviations:
* `eq` ≈ equal
* `ne` ≈ not equal.
* `ge` ≈ greater than or equal.
* `gt` ≈ greater than
* `le` ≈ less than or equal.
* `lt` ≈ less than
Shorthands:
* `reader` ≈ implements `.read_to_string(…)` such as `std::io::Read`.
* `matcher` ≈ implements `.is_match(…)` such as `regex::Regex`.
* `containee` ≈ usable inside `.contains(…)` such as a
`std::string::String` substring.
* `set` ≈ a collection such as `::std::collections::BTreeSet`.
* `bag` ≈ a collection such as `::std::collections::BTreeMap` which has
key counts.