Shifts data from the stack

@param {String} args The arguments to the command
@constructor
function ReadCommand(args) {
    var parsed = new statements.ArgumentStatement(args);
    for (var i = 0; i < parsed.args.length; i++) {
        var placeVar = parsed.args[i];
        if (!(placeVar.child instanceof statements.VariableStatement || placeVar.child instanceof statements.FunctionStatement))
            throw new SyntaxError('Expected variable');
    }
    this.items = parsed.args;
}