code: def xdr(self):
          
          asset = Xdr.StellarXDRPacker()
          asset.pack_Asset(self.to_xdr_object())
          return base64.b64encode(asset.get_buffer())
docs: Create an base64 encoded XDR string for this :class:`Asset`.
  
          :return str: A base64 encoded XDR object representing this
              :class:`Asset`.