Places an order for the specified amount of carbon credits (in kilograms), or for the specified total price (in USD cents).
The order will remain in the placed state until it can be matched to available credits,
after which the order will be fulfilled and moved to the fulfilled state.
If specifying total price, we will determine the amount of carbon credits based on the unit price of the portfolio used for the order.
Because the amount must be an integer number of kilograms, the final actual total price might be slightly different than the specified total price.