recreating my first CRUD in python, but now more professional

At first, and I think the most obvious, I used python language to construct all the system. Now, going beyond the obviously I would like to demonstrate the Orientation Object (OO) system, was created in the base two classes which one is instantiated to create Menu object, and the other one is the Client which one is instantiated to create the object Client with name and birth date, the age is calculated automated by the class. In addition, the project was made thinking by the Test Drive Development (TDD) method and all the code was thought for the easy and quick maintenance.

This object is made by a constructor with two instances, name and birth date. At first, in the input field the information typed by the user receive a small treatment eliminating all the spaces in the begging and in the end by the .strip() function, at the same moment other small treatment is applied for the Title() function, after that the input content is conducted to the object constructor to be instantiated. The name is validated automatically, if the user types a number among the string array the object will not be create and an error gone be raised to the user informing the problem, after the validation if everything is ok so the object receives the attribute name.

The attribute birth date in the constructor work for two information. At first the date typed in the input field goes to a validator, an intern method to verify if the date format in in the standard and if it's valid, cause if the input field content "30/02/2002", for example, an error gone be raised to the user informing this kind of date is invalid (because February goes until 28th or 29th). After the validation, if everything is ok the date in the format dd/mm/yyy gone be returned to the "self.bith_date" attribute. After this validation the same information is donated to other inter method, the age generator. This inters method uses the birth date information and the actual date to calculate the age in the construction of the object. An important point is, if the attribute be invocated in other moment the age calc is made again, so the age will not be the same of the construction, for this this attribute receive a getter method, the first to protect and avoid being instantiated out of the class; all time this getter is invocated, the getter use the intern method to calculate based in the birth date, which is static.