Its cute that you want to invent new ways to interact with a Dictionary but
# This is strictly how you set values
dict.key = "value"
dict["key"] = "value"
dict = {"key" : "value"}
The purpose of get is for comparisons sake or when you need a defualt value
var dict = {
"one" : "1"
}
func _ready():
if dict.get("two", "0") != "0":
print (dict.two)
$Label.text = dict.get("two", "2")