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.
In most cases, the front of the foot is twisted downward and inward, the arch is increased, and the heel is turned inward. Untreated, the foot can't move up and down as it normally would, and this can cause the child to walk on the side of the foot. If your child has clubfoot, here's what it might look like.