Write a csv file.

def csv_writer(molecules, options, prefix):
    """
	Write a csv file.
	"""

    # output file
    outdir = os.getcwd()
    filename = prefix + '.csv'
    outfile = os.path.join(outdir, filename)

    # initiate csv writer object
    f = open(outfile, 'w')
    csv_writer = csv.writer(f)

    # write csv header
    mol = molecules[0]
    write_csv_header(mol, csv_writer)

    # write csv lines
    for mol in molecules:
        write_csv_line(mol, csv_writer, options)

    # close file
    f.close()