## Declaration part
Keywords: patterns

The first thing you should do in this part is to instantiate the class `Patwrite` to have access to all patterns declaration and description methods. The constructor of this class take as parameters the name of pattern output file and the Stratus cell that is described (see `PatWrite` 3.1).
Then, this part allows you to declare the inputs, the outputs, and internal observing points (see `declar` 3.4 and `declar_interface` 3.3).