http://ballpython.ca/genetics.html

The text below can be applied to any simple recessive gene:
piebald, albino, axanthic, genetic stripe, hypo(ghost), lavender albino, caramel albino, etc.

this page may help you a lot. Pieds, or piebald is a simple recessive mutation. This means, that both parent animals need to have at least one copy of the gene in question to have the possibility of producing offspring that not only carry the gene, but display the trait that it carries.

Hets, or heterozygous animals, are animals that CARRY the gene but do not display it. They look completely normal. You can not tell which animals in a clutch are hets unless you bred a visual animal (in this case a pied) to a female. ALL the offspring produced would have one copy of the gene (in this scenario it came from dad) so they would be 100% het/heterozygous pied.

100% hets - animals known to be carrying the questioned gene.

66% hets - these animals are produced by breeding two 100% hets together. Once they are proved out by breeding, they either ARE heterozygous or NOT heterozygous for the gene in question. This does not mean that 66% of the babies will be pied/carry the pied gene/etc.

50% or possible hets - these animals are produced by breeding a 100% het animal to a normal animal. The babies have a 50% chance of carrying the gene in question. Like the 66% hets, these guys need to be proven to be het or not by breeding