/**
 * Coerces a given string value to a number (if valid).
 *
 * @function
 * @name toNumber
 * @param {string} val A string value to coerce to a number
 * @returns {number|undefined} A numeric representation of the original value, or `undefined` if it cannot be coerced to a number.
 */
export default function toNumber(val: string): number | undefined