/**
 * Base URL for Wallet API endpoints
 */
export declare const BASE_URL = "https://api.helius.xyz/v1/wallet";
/**
 * Build a query string from parameters, filtering out undefined and null values
 *
 * @param params - Object with query parameters
 * @returns Query string with leading '?' or empty string
 *
 * @example
 * ```ts
 * buildQueryString({ "api-key": "test", page: 1, unused: undefined })
 * // Returns: "?api-key=test&page=1"
 * ```
 */
export declare const buildQueryString: (params: Record<string, unknown>) => string;
/**
 * Handle fetch response with error checking
 *
 * Checks for HTTP errors and API-level errors in the response body.
 * Throws an error if either is found, otherwise returns the parsed JSON.
 *
 * @param res - Fetch Response object
 * @returns Parsed JSON response
 * @throws Error if HTTP error or API error
 *
 * @example
 * ```ts
 * const response = await fetch(url);
 * const data = await handleResponse<MyType>(response);
 * ```
 */
export declare const handleResponse: <T>(res: Response) => Promise<T>;
/**
 * Get standard headers for Wallet API requests
 *
 * @param includeContentType - Whether to include Content-Type header (for POST requests)
 * @returns Headers object
 *
 * @example
 * ```ts
 * // For GET requests
 * const headers = getHeaders();
 *
 * // For POST requests
 * const headers = getHeaders(true);
 * ```
 */
export declare const getHeaders: (includeContentType?: boolean, userAgent?: string) => Record<string, string>;
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