Names for data structures have the same overt structure as a Metaphor System𓇯: one thing (an `Invoice` data structure) is said to be "the same as" another thing (actual invoices).
Metaphors assert some sort of correspondence between one thing and another, frequently with the intention of understanding some abstract thing ("love") in more concrete terms ("is a journey").
Reason about (understand, solve problems with) love using concepts from an understanding of journeys.
In theory, then, one could understand or reason about an `Invoice` class using knowledge of real-world invoices.
Spoiler: my issue in Programmers Don't Much Use Metaphor𓅮 will turn out to be that we don't actually use the Source Domain𓇯 (business invoices) to reason about the Target Domain𓇯 (the `Invoice` class).