Function keyValuePair

src/math-json/utils.ts:202–214

(
  expr: MathJsonExpression | null | undefined
)

}

function keyValuePair(
  expr: MathJsonExpression | null | undefined
): null | [key: string, value: MathJsonExpression] {
  const h = operator(expr);
  if (h === 'KeyValuePair' || h === 'Tuple' || h === 'Pair') {
    const [k, v] = operands(expr);
    const key = stringValue(k);
    if (!key) return null;
    return [key, v ?? 'Nothing'];
  }

  return null;
}

// Parse the expression either as:
// - a `Dictionary` expression