from __future__ import division

def setup():
    size(400,400)
    background(255)

def draw():
    background(255)
    cline([0,20],[100,21])

def cline(a,b):
    a = list(a)
    b = list(b)
    if a[0] > b[0]: a[0], b[0] = b[0], a[0]
    if a[1] > b[1]: a[1], b[1] = b[1], a[1]

    if a == b: point(a[0], a[1])
    elif a[0] == b[0]:
        for y in range(a[1], b[1]+1): point(a[0], y)
    elif a[1] == b[1]:
        for x in range(a[0], b[0]+1): point(x, a[1])
    else:
        vdif = (b[1]-a[1])/(b[0]-a[0])
        y = a[0]
        for x in range(a[0], b[0]+1):
            point(x,y)
            y += vdif