Twitter Inc. on Tuesday issued a fact-check warning on President Donald Trump's tweets that called mail-in ballots "fraudulent," angering the U.S. leader who has used social media as a powerful tool to attack opponents and get his message across to supporters.It is the first time Twitter has used a blue exclamation mark, advising users "get the facts," below tweets sent by Trump, who has more than 80 million followers on the platform.A spokesperson for Twitter said it took action based on a system introduced this month, because the tweets "contain potentially misleading information about vo…READ FULL ARTICLE