How to use the biothings.utils.common.safewfile function in biothings

def file_merge(infiles, outfile=None, header=1, verbose=1):
    '''merge a list of input files with the same format.
       if header will be removed from the 2nd files in the list.
    '''
    outfile = outfile or '_merged'.join(os.path.splitext(infiles[0]))
    out_f, outfile = safewfile(outfile)
    if verbose:
        print("Merging...")
    cnt = 0
    for i, fn in enumerate(infiles):
        print(os.path.split(fn)[1], '...', end='')
        line_no = 0
        in_f = anyfile(fn)
        if i > 0:
            for k in range(header):
                in_f.readline()
        for line in in_f:
            out_f.write(line)
            line_no += 1
        in_f.close()
        cnt += line_no
        print(line_no)

def _fetch_data(self, outfile, attributes, filters='', header=None, debug=False):
        cnt_all = 0
        out_f, outfile = safewfile(outfile, prompt=(not self.no_confirm), default='O')
        if header:
            out_f.write('\t'.join(header) + '\n')
        logging.info('Dumping "%s"...' % os.path.split(outfile)[1])
        for species in self.species_li:
            dataset = self.get_dataset_name(species)
            taxid = species[2]
            if not dataset:
                continue
            xml = self._make_query_xml(dataset, attributes=attributes, filters=filters)
            if debug:
                logging.info(xml)
            try:
                con = self.query_mart(xml)
            except MartException:
                import traceback
                err_msg = traceback.format_exc()

def write_mapping_file(mapping_generator, outfile, confirm=True):
    """OUTPUT is mapping file:
    -------------------------
    Note: you will not know the source of the mapping unless you use
    the optional parameter "add_source=True" to merge_mapping() function
    col0: Ensembl gene ID
    col2 "add_source" == 1: NCBI ID gene ID from gene2ensembl
    col2 "add_source" == 2: NCBI ID gene ID from ncbi_list if symbol == ensembl symbol
        (i.e. iterate through ncbi list (for each Ensembl ID) on gene_info file
        and when the symbol found matches the ensembl symbol use this
        NCBI ID if symbols match only once)
    """
    print("step 6 start: write file from mapping generator of tuples")
    mapping_file, mapping_filename = safewfile(outfile, prompt=confirm,default='O')

    count = 0
    for item in mapping_generator:
        count += 1
        split_item = list(item)
        split_item = '\t'.join([str(i) for i in split_item])
        mapping_file.write(split_item + "\n")

    print("total Ensembl IDs uniquely mapped to NCBI gene ID:", count)
    mapping_file.close()
    print("Output file: \"{}\"".format(mapping_filename))
    print("step 6 end\n")
    return count

def _fetch_data(self, outfile, attributes, filters='', header=None):
        out_f, outfile = safewfile(outfile, prompt=False, default='O')
        if header:
            out_f.write('\t'.join(header) + '\n')
        failed = []
        def do(species_li, keep_failed=True):
            cnt_lines_all = 0
            cnt_species_success = 0
            for count, species in enumerate(species_li):
                try:
                    dataset = self.get_dataset_name(species)
                except IndexError:
                    self.logger.debug("Skip species '%s'", species)
                    continue
                if not dataset:
                    continue
                taxid = species[2]
                xml = self._make_query_xml(