#!/bin/usr/env python
"""
Script to rudementarally model spiders colonising new terrain, and the effect
that could have on increasing the nutrient levels.
"""

import numpy as np

class Terrain:
    """ Terrain class represents the terrain over which the model is run. """

    def __init__(self, size_x=10, size_y=10):
        """ Create a new field of size_x by size_y """
        self.field = np.zeros(shape=(size_x, size_y))

    def print_terrain(self):
        """ Display the field """
        print(self.field)


class Critter:
    """ Basic class for a creature that can appear, modify the terrain, and
    procreate or die. """

    def __init__(self, nutrient_value=1):
        self.nutrient_value = nutrient_value

    def expire(self):
        """ Death of the critter """
        return self.nutrient_value


def main():
    """ main function, do stuff """

    board = Terrain()
    board.print_terrain()

    spider1 = Critter()

    print("\nSpider1 left", spider1.expire(), "nutrients behind.")


if __name__ == '__main__':
    main()