To draw a weeping tree, start with a trunk. The trunk should allow 2 branches to grow from its top end. Each following branches should allow for the same, but have increasing chance to grow a branch that grows downwards. Every time a branch is created, its length should be reduced by a little. As long as a branch is longer than 10 units, it can grow another branch. Every time a branch is created, it should also use a lighter colour.