The API doesn't let you set the progress, you must know in advance how many steps there are and then call the increment function that exact number of steps. Thi

The API doesn't let you set the progress, you must know in advance how many steps there are and then call the increment function that exact number of steps. This is not conducive to, for example, a network transfer where you have some total number of bytes, and then you receive a packet of some arbitrary size and you want to set the progress to a percent.