Augment this plan constructed in this world for this merchant with the :quantity of goods which should be bought and the :expected-profit of the trade.

Returns the augmented plan.

The total weight of the current cargo carried by this merchant in this world.

Find the price anticipated, given this world, by this merchant for this commodity in this city. If no information, assume 1. merchant should be passed as a map, commodity and city should be passed as keywords.

Find the best destination in this world for this commodity given this merchant and this origin. If two cities are anticipated to offer the same price, the nearer should be preferred; if two are equally distant, the ones nearer to the merchant’s home should be preferred. merchant may be passed as a map or a keyword; commodity should be passed as a keyword.

The returned plan is a map with keys:

• :merchant - the id of the merchant for whom the plan was created;
• :origin - the city from which the trade starts;
• :destination - the city to which the trade is planned;
• :commodity - the commodity to be carried;
• :buy-price - the price at which that commodity can be bought;
• :expected-price - the price at which the merchant anticipates that commodity can be sold;
• :distance - the number of stages in the planned journey
• :dist-to-home - the distance from destination to the merchant’s home city.

A merchant, in a given location in a world, will choose to buy a cargo within the limit they are capable of carrying, which they can anticipate selling for a profit at a destination.