Forces of many charges in code

You will write three functions that find forces between charges on a line. They use Coulomb's law and the principle of superposition.

The idea. The force between two charges is $F = kq_1q_2/r^2$. Like charges repel. Unlike charges attract. We give a force a plus sign when it pushes towards $+x$ and a minus sign when it pushes towards $-x$.

Your tasks.

1. In force_from, return the force on a charge q at x that is caused by one other charge q_other at x_other. All positions are in m on a line.
2. In net_force, others is a list of pairs (charge, position). Return the net force on q at x, which is the sum of the forces from all the others.
3. In zero_point, two positive charges q1 at x = 0 and q2 at x = d are fixed. Return the distance from q1 of the point between them where the net force on a small positive charge is zero.