All the wiki says is:
Sets values on the pressure map, 3 overloads
tpt.set_pressure(number x, number y)
tpt.set_pressure(number x, number y, number width, number height)
tpt.set_pressure(number x, number y, number width, number height, number value)
But what is an "overload"? And how do you add something like 50 pressure to a single pixel?