Checks if the input data can be handled by this class. Throws an error if it can't handle the data.
Input data that could potentially be handled.
A promise resolving if the input can be handled, rejecting with an Error if not.
Input data that will be handled if it can be handled.
A promise resolving if the input can be handled, rejecting with an Error if not. Return value depends on the given type.
A VariableHandler that will set the given variable to the given value, unless there already is a value for the variable and override is false.