The word attrib is a keyword. Indeed, we want to make sure
that the programmer starts the implementation of a domain by
defining the representation of the elements of this domain.
This is why we have a rule:
We also want attrib to be a reserved word, with its own token.
Therefore, it is convenient to have a rule for an attrib call,
that is when we create an element of the actual class.
In addition, we need to say that an
ElementCreation is a statement: