createCommand
Create a Command from a given function, for use with ViewModels.
A Command is a function with an extra canExecute observable property to determine whether the command can be executed. When executed, a Command function will check the value of canExecute and throw if false. It also provides events for when a command has been or is about to be executed.
Parameters
func
The function to execute.
canExecute
A boolean indicating whether the function can currently be executed. Default value - true