def list_unspent(oa_address_list = [])
      btc_address_list = oa_address_list.map { |oa_address| oa_address_to_address(oa_address)}
      outputs = get_unspent_outputs(btc_address_list)
      result = outputs.map{|out| out.to_hash}
      result
    end
def list_unspent(oa_address_list = [])
      btc_address_list = oa_address_list.map { |oa_address| oa_address_to_address(oa_address)}
      outputs = get_unspent_outputs(btc_address_list)
      result = outputs.map{|out| out.to_hash}
      result
    end
get UTXO for colored coins.
 @param [Array] oa_address_list Obtain the balance of this open assets address only, or all addresses if unspecified.
 @return [Array] Return array of the unspent information Hash.