Returns a tuple from BookInfo featuring Market Depth entries for the specified symbol.
[in] Financial instrument name. Required unnamed parameter.
Returns the Market Depth content as a tuple from BookInfo entries featuring order type, price and volume in lots. BookInfo is similar to the MqlBookInfo structure.
Return None in case of an error. The info on the error can be obtained using last_error().
The subscription to the Market Depth change events should be preliminarily performed using the market_book_add() function.
The function is similar to MarketBookGet.