class Student:
    '''A student with a name, age, and major.'''
    
    def __init__(self, name, age, major):
        '''Initializes the student object.'''
        self.name = name
        self.age = age
        self.major = major
        
    
    def birthyear(self):
        '''Return the student's year of birth.'''
        return 2016 - self.age


    def switch_major(self, new_major):
        '''Changes the student's major to new_major'''
        self.major = new_major

########################

import math
        
class Point:        # or equivalently,  class Point(object):
    '''Represent an (x, y) coordinate pair.'''
    
    def __init__(self, new_x, new_y):
        '''Set up a new Point object with an x and y value.'''
        self.x = new_x
        self.y = new_y
    
    
    def distance_to(self, other_point):
        '''Return the distance from this point to other_point.'''
        x1 = self.x
        y1 = self.y
        x2 = other_point.x
        y2 = other_point.y
        return math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)
    
    
    def distance_origin(self):
        '''Return the distance from this point (aka self) to the origin.'''
        origin = Point(0, 0)
        return self.distance_to(origin)
    
    
class LineSegment:
    '''A line segment from one point to another point.'''
    
    def __init__(self, start_point, end_point):
        '''Initializes the line segment by storing the start and endpoints.'''
        self.start_point = start_point
        self.end_point = end_point
    
    
    def slope(self):
        '''Return the slope of the line segment.'''
        change_y = self.end_point.y - self.start_point.y
        change_x = self.end_point.x - self.start_point.x
        return change_y / change_x
    
    
    def length(self):
        '''Return the length of the line segment.'''
        return self.start_point.distance_to(self.end_point)