/**
 * Returns true if the GraphQL document contains a mutation operation that
 * would actually be executed for the given (optional) operation name.
 *
 * - When `operationName` is provided, only the matching operation is checked.
 * - When `operationName` is omitted and the document has a single operation,
 * that operation is checked.
 * - When the document has multiple operations and no operation name is given,
 * any mutation in the document is treated as a mutation request (the GraphQL
 * server would reject the ambiguous request anyway).
 *
 * Returns false for queries, subscriptions, fragment-only documents, and any
 * input that fails to parse as GraphQL.
 *
 * @param query - The GraphQL document to inspect.
 * @param operationName - Optional name of the operation to check; when set, only that operation is considered.
 * @returns True if the relevant operation is a mutation; false otherwise.
 */
export declare function containsMutation(query: string, operationName?: string): boolean;