pub trait Numeral {
fn is_numeral(&self, prism: AnchoredLine) -> bool { ... }
fn inc(&self, prism: AnchoredLine) -> Unit { ... }
fn dec(&self, prism: AnchoredLine) -> Unit { ... }
fn add(&self, prism: AnchoredLine, other: Unit) -> Unit { ... }
fn subtract(&self, prism: AnchoredLine, other: Unit) -> Unit { ... }
fn neg(&self, prism: AnchoredLine) -> Unit { ... }
fn multiply(&self, prism: AnchoredLine, other: Unit) -> Unit { ... }
fn divide(&self, prism: AnchoredLine, other: Unit) -> Unit { ... }
fn remainder(&self, prism: AnchoredLine, other: Unit) -> Unit { ... }
fn modulus(&self, prism: AnchoredLine, other: Unit) -> Unit { ... }
}