Helper function to extract N: and C: rows from annotations and pad their values

def annotation_rows(prefix, annotations):
    """
    Helper function to extract N: and C: rows from annotations and pad their values
    """
    ncol = len(annotations['Column Name'])
    return {name.replace(prefix, '', 1) : values + [''] * (ncol - len(values))
            for name, values in annotations.items() if name.startswith(prefix)}