type RecoveryParam = number | null | undefined;
 
interface SignatureOptions {
  r: BN;
  s: BN;
  recoveryParam: RecoveryParam;
}
 
function exportRecoveryParam(recoveryParam: RecoveryParam): string | null;
 
function importRecoveryParam(v: string): number | undefined;
 
function serializeSignature(sig: SignatureOptions): string;
 
function deserializeSignature(sig: string, size = 64): SignatureOptions;