code: def add_vertex(self, x, y, z):
          
          self.vert_data.write(
              struct.pack('<f', x) +
              struct.pack('<f', y) +
              struct.pack('<f', z)
          )
  
          # retain min/max values
          self.vert_min = _list3_min(self.vert_min, (x, y, z))
          self.vert_max = _list3_max(self.vert_max, (x, y, z))
docs: Add a ``VEC3`` of ``floats`` to the ``vert_data`` buffer