Such *section classes* can then be instantiated like regular Python classes. Respectively, *section instances* are just regular Python object and section quantities can be get and set like regular Python object attributes.
Of course the metainfo is not just about dealing with physics data in Python. Its also about storing and managing data in various fileformats and databases. Therefore, the created data can be serialized, e.g. to JSON. All *section
instances* have a set of additional `m_`-methods that provide addtional functions. Note the unit conversion.
Since all definitions are available as *section classes*, Python already knows about all possible quantities. We can
use this in Python notebooks, via *tab* or the `?`-operator. Furthermore, you can access the *section definition* of all *section instances* with `m_def`. Since a *section defintion* itself is just a piece of metainfo data, you can use it to programatically explore the definition itselve.