qml learning: Unexpected token `:'

QML new version format

Since I am using qt5.9.9 QML format is 3, the previous function variable writing is not supported, the following is an error:

signal clicked(cellColor:color)

The above code reported an error. I wrote this according to the official website routine and checked the information, which means that the QML version has changed. The
correct writing: name: type is as follows

signal clicked(color cellColor)