According to researchers, a coin flip may not have a 50% chance of landing heads and a 50% chance of landing tails. In fact, they believe that a coin is more likely to land the same way it started. So if it starts out heads up, it is more likely to land heads up. Suppose someone tests this hypothesis with 1,000 flips of a coin where it starts out heads up each time. Describe what the symbol π stands for in this context.