/**
 * Converts a string to Sentence Case.
 *
 * @example
 * toSentenceCase("hello world") // "Hello world"
 * toSentenceCase("CamelCaseString") // "Camel case string"
 * toSentenceCase("") // ""
 *
 * @param str The string to convert to Sentence Case.
 * @returns The Sentence Case version of the input string.
 */
export declare function toSentenceCase(str: string): string;