does this price include flushing the old trans fluid from the transmission

What is your question?

i understand that most places just drain the trans fluid and then replace it with new fluid which still leaves a fairly signifigant amount of used fluid in the trans. One shop I talked to said the use a machine that pumps 12 quarts of new fluid through the trans after the empty the old fluid and before they add the new fluid. Is this common and or true / necessary?