Examining Facebook's proposed digital currency and data privacy considerations : hearing before the Committee on Banking, Housing, and Urban Affairs, United States Senate, One Hundred Sixteenth Congress, first session, on examining Facebook, Inc.'s planned currency Libra, its governing Libra Association, and the Calibra digital wallet, including the structure and management of Libra and its underlying financial infrastructure and the partners and governance of Libra Association, July 16, 2019