'Merging multiple XML files is non-trivial and must be done in subclasses.'

@staticmethod
def merge(split_files, output_file):

    if (len(split_files) > 1):
        raise NotImplementedError(('Merging    multiple    XML    files    is    non-trivial    ' + 'and    must    be    implemented    for    each    XML    type'))
    data.Text.merge(split_files, output_file)
