class Rectangle:
    """
    A class to represent a rectangle.

    Attributes
    ----------
    x1 : (int) bottom left x-coordinate
    y1: (int) bottom left y-coordinate
    x2 : (int) top right x-coordinate
    y2: (int) top right y-coordinate

    Methods
    -------
    area(): (int) returns the area of the rectangle
    """

    def __init__(self, x1, y1, x2, y2):
        """
        Creates a two-dimensional rectangle and sets its bottom left and top right coordinates
        :param x1: (int) bottom left x-coordinate
        :param y1: (int) bottom left y-coordinate
        :param x2: (int) top right x-coordinate
        :param y2: (int) top right y-coordinate
        """
        self.x1 = x1
        self.y1 = y1
        self.x2 = x2
        self.y2 = y2

    def area(self):
        """
        Returns the area of the rectangle
        :return: (int) the area of the rectangle
        """
        width = abs(self.x2 - self.x1)
        height = abs(self.y2 - self.y1)

        return width * height

    def __str__(self):
        """

        Returns string representation of rectangle
        :return: (str) "The four coordinates of the rectangle are: x1: ... and its area is: (area)"
        """
        return "The four coordinates of the rectangle are: x1: " + str(self.x1) +\
            " , y1: " + str(self.y1) + " , x2: " + str(self.x2) + " , y2: " + \
            str(self.y2) + " and its area is: " + str(self.area()) + " units."


def main():
    rect = Rectangle(0, 0, 10, 20)
    print(rect)

if __name__ == "__main__":
    main()