"""Coin flip histogram: the number of heads in 20 flips, stacked in coins.
Each trial flips twenty coins and counts the heads. Instead of a bar, every
count gets a stack of coins, and each trial throws one more coin onto the
stack for its count, so the histogram is built out of the things being
counted. The stacks settle into the binomial's bell, tight around ten; the
reference toggle stands the binomial itself on the wall behind them.
Every trial is drawn from one seed up front, so the stacks in the still are
the stacks the loop ends on. The loop is a oneshot: stacks only grow, and
the last few coins are still in the air when it ends, which is the still.
Counts below 3 or above 17 are left off the row. Out of the 480 trials they
would expect about a tenth of a coin between them, and leaving them out is
what lets the stacks be wide enough to read as coins.
The full Manim source and the rendered video come with a plan.
