已知两条直线上各两点坐标，求两条直线交点坐标

def point(x0,y0,x1,y1,x2,y2,x3,y3):
a = y1-y0
b = x1*y0-x0*y1
c = x1-x0
d = y3-y2
e = x3*y2-x2*y3
f = x3-x2
y = float(a*e-b*d)/(a*f-c*d)
x = float(y*c-b)/a
pt = Point(x,y)
return pt