import { IAsyncStorage } from './storage';
import type { Coin } from '@cosmjs/amino';
/**
 * The `FeeMarketAPI` class provides methods to get fee market gas prices.
 */
export declare class FeeMarketAPI {
    private static cache;
    private static activeRequests;
    /**
     * Checks if the cache has been initialized.
     * @returns `true` if the cache is initialized, `false` otherwise.
     */
    static isCacheInitialized(): boolean;
    /**
     * Initializes the cache for storing fee market gas prices.
     * @param storage - An implementation of `IAsyncStorage` interface.
     */
    static initializeCache(storage: IAsyncStorage): void;
    /**
     * Retrieves the fee market gas prices from the given LCD URL.
     * It initializes the cache if not already initialized and caches the fetched data.
     * @param lcdUrl - The URL of the LCD endpoint to get the gas prices from.
     * @param expiryDuration - The duration in milliseconds for which the prices should be cached.
     * @returns A list of the gas prices, or an empty array if the prices cannot be fetched.
     */
    static getFeeMarketGasPrices(lcdUrl: string, expiryDuration?: number): Promise<Coin[]>;
}