 Complete the following phrase:  Twitter has been used for a variety of purposes in many industries and scenarios. For example, it has been used to organize protests, sometimes referred to as Twitter Revolutions, which include the protests over the 2009 Moldovan election, the 2009 student protests in Austria, the 2009 GazaIsrael conflict, the 2009 Iranian green revolution, the 2010 Toronto G20 protests, the 2010 Bolivarian Revolution, the 2010 Stuttgart21 protests in Germany, the 2011 