Metallica and Lang Lang rehearse for THE 56TH ANNUAL GRAMMY AWARDS music industry's premier event takes place Sunday, Jan. 26 (8:00-11:30 PM, live ET/delayed PT) at STAPLES Center in Los Angeles on the CBS Television Network. Photo: Heather Wines/CBS ©2014 CBS Broadcasting, Inc. All Rights Reserved

Grinders are on display for sale during the HempCon 2011 Medical Marijuana Expo at the Los Angeles Convention Center on August 26, 2011 in Los Angeles, California. The three-day event includes exhibits, evaluation services, legal services, equipment, and accessories. (Photo by Kevork Djansezian/Getty Images)

The Ray and Maria Stata Center is shown on the campus of the Massachusetts Institute of Technology February 22, 2006 in Cambridge, Massachusetts. The Institute admitted its first students in 1865 and continues with the mission to advance knowledge and educate students in science, technology, and other areas of scholarship. (Photo by Joe Raedle/Getty Images)

The Facebook website is displayed on a laptop computer on May 9, 2011 in San Anselmo, California. An investigation by The Pew Research Center found that Facebook has become a player in the news industry as the popular social media site is driving an increasing amount of traffic to news web sites. (Photo Illustration by Justin Sullivan/Getty Images)

Crowds gather and watch the launch of NASA space shuttle Endeavour from Kennedy Space Center on the beach May 16, 2011 in Cocoa Beach, Florida. (Photo by Roberto Gonzalez/Getty Images)

Lady Gaga attends the 2011 CFDA Fashion Awards at Alice Tully Hall, Lincoln Center on June 6, 2011 in New York City. (Photo by Andrew H. Walker/Getty Images)

Singer Donni Rai arrives at the 48th Annual Grammy Awards at the Staples Center on February 8, 2006 in Los Angeles, California. (Photo by Stephen Shugerman/Getty Images)

In this July 15, 2015 photo, Nepalese amputee victims Khendo Tamang, left, and Nirmala Pariyar, both 8, share a single pair of shoes at the Bir Trauma Center in Kathmandu, Nepal. After suffering serious leg wounds in Nepal's massive 2015 earthquake that killed and injured thousands, both girls were brought to the Bir Trauma Center in Kathmandu, to receive single leg amputations. Following their surgeries, Nirmala's relentless cheerfulness drew a still very depressed Khendo close and both found an inseparable friendship which has helped their emotional wounds heal. (Photo by Niranjan Shrestha/AP Photo)