/**
 * Lowercase the first character of a string
 * @example "UserProfile" -> "userProfile"
 */
export declare function lcFirst(str: string): string;
/**
 * Uppercase the first character of a string
 * @example "userProfile" -> "UserProfile"
 */
export declare function ucFirst(str: string): string;
export declare function toPascalCase(str: string): string;
export declare function toCamelCase(key: string, stripLeadingNonAlphabetChars?: boolean): string;
export declare function isValidIdentifier(key: string): boolean;
export declare function isValidIdentifierCamelized(key: string): boolean;
export declare function toSnakeCase(str: string): string;
export declare function toKebabCase(str: string): string;
export declare function toConstantCase(str: string): string;