/**
 * Validates a variable name according to JSON property name rules.
 * Also allows `$` as a valid identifier character to support loop
 * references (e.g. `$.item.name`, `$.index`).
 *
 * Valid: user.firstName, company.address.street, _private, user123, $.item.name, $.index
 * Invalid: user. firstName (space), user. (trailing dot), user..name (double dot), 123invalid (starts with digit)
 *
 * @param variableName - The variable name to validate (without curly braces)
 * @returns true if the variable name is valid, false otherwise
 */
export declare function isValidVariableName(variableName: string): boolean;