def _gen_csv_data(self, f, dialect):
		"""
		Yields (column data, row number) tuples from the given csv file
		handler, using the given Dialect named tuple instance. Depends on
		self.ipa_col being correctly set.

		Helper for the gen_ipa_data method.
		"""
		reader = self._get_csv_reader(f, dialect)

		for line in reader:
			try:
				datum = line[self.ipa_col]
			except IndexError:
				mes = 'Could not find IPA data on line: {}'.format(line)
				raise ValueError(mes)

			yield datum, reader.line_num