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.
Most children begin walking at 12 to 14 months with their feet flat on the ground. However, there are some children who begin walking on their tip toes instead. This pattern normally disappears within 3 to 6 months of learning how to walk. It almost always is completely gone by the end of the third year. Idiopathic toe walking is when a child continues to walk on his tip toes beyond 3 years of age. He will often stand with his feet flat on the ground, but when walking or running will prefer to be on his toes. If your child does not outgrow tip toe walking by 3 years of age, take him to see a health care professional.