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.
Flat feet (pes planus) refer to a change in foot shape in which the foot does not have a normal arch when standing. Flat feet are a common condition. The condition is normal in infants and toddlers. Flat feet occur because the tissues holding the joints in the foot together (called tendons) are loose. The tissues tighten and form an arch as children grow older. This will take place by the time the child is 2 or 3 years old. Most people have normal arches by the time they are adults.