/**
 * Converts `string`, as space separated words, to upper case.
 *
 * upperCase('--foo-bar') // => 'FOO BAR'
 * upperCase('fooBar') // => 'FOO BAR'
 * upperCase('__foo_bar__') // => 'FOO BAR'
 */
export declare const upperCase: (input: string) => string;