You can read from the "text" member if you like instead of using get_text()

[jaynabonne]

A minor note: to read the line edit text value, you don’t have to use

var new_text = $Blackboard/LineEdit.get_text()

You can just as easily use

var new_text = $Blackboard/LineEdit.text

as you did when assigning it. At least, it worked for me!