/**
 * @file
 *
 * Converts a function into a string that is a valid function expression.
 */
/**
 * Converts a function into a string that is a valid function expression.
 *
 * `Function.prototype.toString()` on a shorthand method like `{ callback() {} }`
 * returns `"callback() {}"`, which is not a valid expression.
 * This helper detects that form and prefixes it with `function `.
 *
 * @param callback - The function to convert.
 * @returns A string that is a valid function expression.
 */
export declare function getFunctionExpressionString(callback: Function): string;