penguinsReduced = model()
.reduce()
.add()
.called("min body mass")
.does((x) => d3.min(x, (d) => d["body_mass_g"]))
.end()
.add()
.called("max body mass")
.does((x) => d3.max(x, (d) => d["body_mass_g"]))
.end()
.add()
.called("avg body mass")
.does((x) => d3.mean(x, (d) => d["body_mass_g"]))
.end()
.groupBy("species", "island")
.end()
.data(penguins)