docs: def select_charset(self, charset):
          '''Select international character set and changes codes in code table accordingly
          
          Args:
              charset: String. The character set we want.
          Returns:
              None
          Raises:
              RuntimeError: Invalid charset.
          '''
          charsets = {'USA':0,
                     'France':1,
                     'Germany':2,
                     'UK':3, 
                     'Denmark':4,
                     'Sweden':5, 
                     'Italy':6, 
                     'Spain':7,
                     'Japan':8, 
                     'Norway':9, 
                     'Denmark II':10, 
                     'Spain II':11, 
                     'Latin America':12, 
                     'South Korea':13, 
                     'Legal':64, 
                     }
          if charset in charsets:
              self.send(chr(27)+'R'+chr(charsets[charset]))
          else:
              raise RuntimeError('Invalid charset.')