Function symbol

src/math-json/utils.ts:186–200

(
  expr: MathJsonExpression | null | undefined
)

}

export function symbol(
  expr: MathJsonExpression | null | undefined
): string | null {
  // Is it a symbol shorthand?
  if (typeof expr === 'string' && matchesSymbol(expr)) {
    if (expr.length >= 2 && expr.at(0) === '`' && expr.at(-1) === '`')
      return expr.slice(1, -1);
    return expr;
  }

  if (expr === null || expr === undefined) return null;

  if (isSymbolObject(expr)) return expr.sym;
  return null;
}

function keyValuePair(
  expr: MathJsonExpression | null | undefined