Any function object that is a class attribute defines a method for instances of that class. It is not necessary that the function definition is textually enclosed in the class definition: assigning a function object to a local variable in the class is also ok.
Most children are born with very little arch in the feet. As they grow and walk, the soft tissues along the bottom of the feet tighten, which gradually shapes the arches of the feet. Children with flexible flatfoot often do not begin to develop an arch until the age of 5 years or older. Some children never develop an arch. If flexible flatfoot continues into adolescence, a child may experience aching pain along the bottom of the foot. A doctor should be consulted if a child's flatfeet cause pain.
The arch of the foot is a very complex structure, consisting of multiple bones and ligaments. Most causes of arch pain are related to the anatomy of the arch and the types of physical activity that you perform. For example, a classic set up for arch pain is people who engage in lots of high impact exercise (such as running) while wearing a type of athletic shoe that does not properly support their type of foot arch.