Function isFunction

src/compute-engine/numerics/interval.ts:28–36

(
  expr: Expression | null | undefined,
  operator?: string
)

}

function isFunction(
  expr: Expression | null | undefined,
  operator?: string
): expr is Expression & FunctionInterface {
  return (
    expr?._kind === 'function' &&
    (operator === undefined || expr!.operator === operator)
  );
}

/**
 * Pure endpoint read for an `Interval` function expression: each endpoint