/**
 * Encodes pico btc to human readable part amount. The hrp amount is defined
 * as the amount of bitcoin as a positive decimal integer with no leading 0s.
 * It is an optional number followed by an optional multiplier letter.
 *
 * The multipliers are:
 * m (milli)   0.001 bitcoin
 * u (micro)   0.000001 bitcoin
 * n (nano)    0.000000001 bitcoin
 * p (pico)    0.000000000001 bitcoin
 *
 * This means that 1msat is 10p and 1sat is 10n.
 */
export declare function encodePico(pico: string): string;