Set a number of values within sub-stores of the value store.
Depending on the type of the value, it is converted to the proper type.
In case the type is function, the value can be one of the following:
add 1: Take the target key from the store, add 1 to it, and store it again. If it did not exist before, initialize with 0 first.substract 1: Take the target key from the store, substrict 1 from it, and store it again. If it did not exist before, initialize with 0 first.+: Add two values together, and store the result as a new value.-: Subtract a value from another value, and store the result as a new value (Second key is subtracted from the first key).*: Multiply two values, and store the result as a new value./: Add a value by another value, and store the result as a new value (First key is divided by the first key).random: Generate a random value between two values (boundaries inclusive), and store the result as a new value. It can be controlled whether or not to round down the resulting value (cutting off any fractional part).