/**
 * Replace every `<mc:AlternateContent>` with the markup its `<mc:Fallback>`
 * holds, so the part reaching the XML parser is plain OOXML in its original
 * element order. A block with no Fallback resolves to nothing — which is what
 * §10.2 of the Markup Compatibility spec asks of a reader that understands
 * none of the offered choices.
 *
 * Text with no AlternateContent is returned unchanged, which is most files.
 *
 * @param xml The decoded part, as read from the package.
 * @returns The part with its compatibility blocks resolved.
 */
export declare function resolveAlternateContent(xml: string): string;