// Grid can customize direction
// Basic trading operation: buy first and then sell.
// The grid will start to send buying order at the price that below the first price, which is the price follow 
// by the first price (second latest buying price, third latest buying price…and so on). Each buying order is separated by
// the "price interval" parameter. The number of pending orders is "single quantity", and will send the order total until
// the "total quantity" is filled.
// After any buying order is completed, the program will be on the basis of the buying price, add the price of the "price
// difference" parameter to the sell price, after the order has been sold, and then re-start the progress of this 
// grid strategy (checking, place order, wait until it executed, sell)
// Selling short first and then buy to cover: the operation is just the opposite
// The biggest risk of this strategy is when the market trend is unilateral moving, and the price fluctuations are exceeding the grid.
// The following code has made the grid with automatic stop loss and movement function.