def opens
      have_key?
      address = @url_private
      body = { "method" => "active_orders" }
      h = post_ssl(address, body)
      h["return"].map{|key, value|
        order_type = "buy" # when value["action"] is "bid"
        order_type = "sell" if value["action"] == "ask"
        {
          "success"    => "true",
          "id"         => key,
          "rate"       => BigDecimal.new(value["price"].to_s),
          "amount"     => BigDecimal.new(value["amount"].to_s),
          "order_type" => order_type,
        }
      }
    end
def opens
      have_key?
      address = @url_private
      body = { "method" => "active_orders" }
      h = post_ssl(address, body)
      h["return"].map{|key, value|
        order_type = "buy" # when value["action"] is "bid"
        order_type = "sell" if value["action"] == "ask"
        {
          "success"    => "true",
          "id"         => key,
          "rate"       => BigDecimal.new(value["price"].to_s),
          "amount"     => BigDecimal.new(value["amount"].to_s),
          "order_type" => order_type,
        }
      }
    end
Get open orders.
 @abstract
 @return [Array] open_orders_array
   @return [hash] history_order_hash
     success: [bool]
     id: [String] order id in the market
     rate: [BigDecimal]
     amount: [BigDecimal]
     order_type: [String] "sell" or "buy"
     order_status: [String] "active", "completed" or "canceled"
   ltimestamp: [int] Local Timestamp