Slope, angle and the angle between lines

You will write three small functions: the slope of a line through two points, the angle it makes with the positive $x$-axis, and the acute angle between two lines. The checker tests them on many pairs of points.

The idea. $m = \dfrac{y_2 - y_1}{x_2 - x_1}$, $m = \tan\theta$, and $\tan\theta = \left|\dfrac{m_2 - m_1}{1 + m_1 m_2}\right|$ for the acute angle between two lines.

Your tasks.

1. Finish slope(p, q). Return None for a vertical line.
2. Finish inclination(p, q): the angle in degrees, from $0$ up to but not including $180$.
3. Finish between(m1, m2): the acute angle in degrees between lines of slopes m1 and m2.