'Set the number of sequences and the number of data lines in dataset.'

def set_meta(self, dataset, **kwd):

    data_lines = 0
    sequences = 0
    for line in open(dataset.file_name):
        line = line.strip()
        if (line and line.startswith('#')):
            continue
        if (line and line.startswith('>')):
            sequences += 1
            data_lines += 1
        else:
            data_lines += 1
    dataset.metadata.data_lines = data_lines
    dataset.metadata.sequences = sequences
