Exercise 2b: Hitman recursion

Given a predicate is_insulting_price, write a recursive function which determines the minimum amount for which a target may be killed without risk of the plot being exposed to the police by an individual receiving a lowball offer. The function will be passed an arbitrarily high value, and should recursively call itself with (1 - epsilon) * price whenever is_insulting_price returns false.

For bonus marks, quantify the tradeoff between error range and stack depth, the latter representing the number of people who need to know about the plot.