function - Understanding objects passed in a class and self calling method in Python -

can me understand python code below. trying figure "output = layer.ingredients(input_)" does? don't understand how class handles object being passed. example, how 1 use parameter in contractor?

class lasagna(layer):       def __init__(self, layers):         self.layers = layers      def ingredients(self, input_):         # remember inputs each layer can use them         self.inputs = []         layer in self.layers:             self.inputs.append(input_)             output = layer.ingredients(input_)             input_ = output         return output  lasagna = lasagna([linear(784, 100), function1(), linear(100, 10), function2()]) 

thanks