move momentum definition to Particle class such that mypy knows about its...

move momentum definition to Particle class such that mypy knows about its existence without setting it to None in FirstInteraction

python/corsika/io/outputs/interaction.py

@@ -36,9 +36,6 @@ class FirstInteraction(Particle):
         """
         Particle.__init__(self, prop_dict)
 
-        # need to define for momentum prop
-        self.px = self.py = self.pz = None
-
     def __repr__(self) -> str:
         """
         Return a string representation of this class.

python/corsika/io/outputs/primary.py

@@ -34,6 +34,7 @@ class Particle(object):
         # need to define for position/direction functions
         self.x = self.y = self.z = None
         self.nx = self.ny = self.nz = None
+        self.px = self.py = self.pz = None
 
         # wrap the files of the dictionary so that there is a property
         # assigned to each value, i.e. print(my_primary.pdg)