Open and return the supplied json file

def load(language_dir, filename, encoding):
  ''' Open and return the supplied json file '''
  global _DICTIONARY
  try:
    json_file = filename + '.json'
    with io.open(os.path.join(language_dir, json_file), 'r', encoding=encoding) as f:
      _DICTIONARY = json.load(f)
  except IOError:
    raise IOError('{0} Language file not found at location {1}. '
                  'Make sure that your translation file is in the '
                  'listed language directory'.format(filename.title(), language_dir))