"""
CS 101 Data Structures examples
"""

def histogram1(s):
    """
    Return dictionary of frequences of characters in string s
    """
    d = dict()
    for c in s:
        if c in d:
            d[c] += 1
        else:
            d[c] = 1        
    return d

def histogram2(s):
    """
    Return dictionary of frequences of characters in string s
    """
    d = dict()
    for c in s:
        d[c] = d.get(c,0)+1
    return d

def vowels(s):
    """
    Test whether all vowels a,e,i,o,u appear in string s
    """
    return set('aeiou') <= set(s)

def overlap(s, t):
    """
    Return set of letters that appear in both strings s and t
    """
    return set(s) & set(t)

class Point:
    """
    Point class has x and y coordinates
    """
    def __init__(self, x=0, y=0):
        self.x = x
        self.y = y
        
import turtle as t

def drawPoints(points):
    """
    Demo of drawing points with the turtle
    """
    for p in points:
        t.goto(p.x, p.y)
        t.dot()