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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _validate_section(self, subject, coll, parts):
 """Validate one section of a spec. :param subject: Name of subject :type subject: str :param coll: The collection to validate :type coll: pymongo.Collection :param parts: Section parts :type parts: Validator.SectionParts :return: Group of constraint violations, if any, otherwise None :rtype: ConstraintViolationGroup or None """

        cvgroup = ConstraintViolationGroup()
        cvgroup.subject = subject

        # If the constraint is an 'import' of code, treat it differently here
        # if self._is_python(parts):
        #    num_found = self._run_python(cvgroup, coll, parts)
        #    return None if num_found == 0 else cvgroup

        query = parts.cond.to_mongo(disjunction=False)
        query.update(parts.body.to_mongo())
        cvgroup.condition = parts.cond.to_mongo(disjunction=False)
        self._log.debug('Query spec: {}'.format(query))
        self._log.debug('Query fields: {}'.format(parts.report_fields))
        # Find records that violate 1 or more constraints
        cursor = coll.find(query, parts.report_fields, **self._find_kw)
        if parts.sampler is not None:
            cursor = parts.sampler.sample(cursor)
        nbytes, num_dberr, num_rec = 0, 0, 0
        while 1:
            try:
                record = next(cursor)
                nbytes += total_size(record)
                num_rec += 1
            except StopIteration:
                self._log.info("collection {}: {:d} records, {:d} bytes, {:d} db-errors"
                               .format(subject, num_rec, nbytes, num_dberr))
                break
            except pymongo.errors.PyMongoError as err:
                num_dberr += 1
                if num_dberr > self._max_dberr > 0:
                    raise DBError("Too many errors")
                self._log.warn("DB.{:d}: {}".format(num_dberr, err))
                continue

            # report progress
            if self._progress:
                self._progress.update(num_dberr, nbytes)
            # get reasons for badness
            violations = self._get_violations(parts.body, record)
            cvgroup.add_violations(violations, record)
        return None if nbytes == 0 else cvgroup