How to use the invenio.bibrecord.record_add_field function in invenio

pubfields.append(('c', remove_html_markup(form['publication_date'])))
        if pubfields:
            record_add_field(rec, '260', subfields=pubfields)
        record_add_field(rec, '856', ind1='0', subfields=[('f', email)])

        if 'open_access' in form:
            record_add_field(rec, '542', subfields=[('l', 'open')])
        else:
            record_add_field(rec, '542', subfields=[('l', 'restricted')])

        if form['licence']:
            record_add_field(rec, '540', subfields=[('a', remove_html_markup(form['licence']))])
        record_add_field(rec, '520', subfields=[('a', remove_html_markup(form['description']))])

        if form['contact_email']:
            record_add_field(rec,'270',subfields=[('m', remove_html_markup(form['contact_email']))])        

        if form['keywords']:
            for kw in form['keywords'].split(','):
                if kw and not kw.isspace():
                    record_add_field(rec, '653',
                                 ind1='1',
                                 subfields=[('a', remove_html_markup(kw.strip()))])

        if 'contributors' in form and form['contributors']:
            fields = form.getlist('contributors')
            for f in fields:
                if f and not f.isspace():
                    record_add_field(rec, '700', subfields=[('a', remove_html_markup(f.strip()))])

        record_add_field(rec, '546', subfields=[('a', remove_html_markup(form['language']))])

if key == 'a':
                        field[0][idx] = ('a', punctuate_authorname(value))

    # 773 is cited by, DOI of the extended paper
    # match the INSPIRE record ID of that paper and add it in 786__w
    for field in record_get_field_instances(rec, '773'):
        subs = field_get_subfields(field)
        if 'i' in subs and 'isSupplementTo' in subs['i']:
            if 'n' in subs and "doi" in [s.lower() for s in subs['n']]:
                paper_recid = perform_request_search(
                    p="0247_a:%s" % subs['a'][0],
                    of="id"
                )

                if paper_recid:
                    record_add_field(rec,
                                     "786",
                                     subfields=[('w', str(paper_recid[0]))])
            if 'n' in subs and "arxiv" in [s.lower() for s in subs['n']]:
                paper_recid = perform_request_search(
                    p="037__a:%s" % subs['a'][0],
                    of="id"
                )

                if paper_recid:
                    record_add_field(rec,
                                     "786",
                                     subfields=[('w', str(paper_recid[0]))])

    # Other mandatory fields
    # 786 formatting
    record_add_field(rec, "786", subfields=[('q', '0')])

def hepdata2marcxml(record):
    out = {}
    record_add_field(out, '024', '7', subfields=[('a', record['doi']), ('2', 'DOI')])
    if record.get('title'):
        title = 'Data from {title} from: {paper_title}'
    else:
        title = 'Additional data from: {paper_title}'
    record_add_field(out, '245', subfields=[('a', title.format(title=record.get('title'), paper_title=record['paper_title'])), ('9', 'HEPDATA')])
    record_add_field(out, '336', subfields=[('t', 'DATASET')])
    record_add_field(out, '520', subfields=[('h', record['abstract']), ('9', 'HEPDATA')])
    for keyword in record['keywords']:
        name = keyword['name']
        value = keyword['value']
        if name in ('observables', 'cmenergies'):
            value = '%s: %s' % (name, value)
        record_add_field(out, '695', subfields=[('a', value), ('9', 'HEPDATA')])
    for collaboration in record['collaborations']:
        record_add_field(out, '710', subfields=[('g', collaboration)])
    record_add_field(out, '786', subfields=[('q', str(record['position'])), ('w', str(record['inspire_id']))])
    record_add_field(out, '980', subfields=[('a', 'DATA')])
    return record_xml_output(out)

fft_status = "firerole: %s" % "\n".join(fft_status)
    for file_path, real_name in files:
        record_add_field(rec, 'FFT', subfields=[
            ('a', file_path),
            #('d', 'some description') # TODO
            #('t', 'Type'), # TODO
            ('m', real_name),
            ('r', fft_status),
        ])
    # License
    if r['license'] == 'CC BY-NC-SA':
        record_add_field(rec, '540', subfields=[
            ('a', 'Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported'),
            ('u', 'http://creativecommons.org/licenses/by-nc-sa/3.0/'),
        ])
        record_add_field(rec, '650', ind1="1", ind2="7", subfields=[
            ('a', 'cc-nc'),
            ('2', 'opendefinition.org'),
        ])
    # DOI
    if r['doi']:
        record_add_field(rec, '024', '7', subfields=[('a', r['doi']), ('2', 'DOI')])

    # Publication date
    record_add_field(rec, '260', subfields=[('c', r['publication_date'])])
    # Title
    record_add_field(rec, '245', subfields=[('a', r['title'])])
    # Creators
    creators = r['authors']
    for (i, name) in enumerate(creators):
        if i == 0:
            field_no = '100'

email = get_email(self.uid)
        name = user_info.get(
            "external_fullname", user_info.get("nickname", "")).strip()
        if isinstance(email, unicode):
            email = email.encode('utf8')
        if isinstance(name, unicode):
            name = name.encode('utf8')
        record_add_field(
            rec, '856', ind1='0', subfields=[('f', email), ('y', wash_for_xml(name))])

        # =================
        # Access right
        # =================
        # Access rights (open, closed, embargoed, restricted date
        access_right = self._metadata['access_right']
        record_add_field(rec, '542', subfields=[('l', access_right)])

        # Embargo date
        if access_right == 'embargoed':
            record_add_field(rec, '942', subfields=[
                ('a', self._metadata['embargo_date'])
            ])

        # =================
        # Type of file(s)
        # =================
        # Upload type - 980__a: type, b: subtype
        main_coll, sub_coll = self.get_collection_name()
        subfields = [('a', main_coll), ]
        if sub_coll:
            subfields.append(('b', sub_coll))
        record_add_field(rec, '980', subfields=subfields)

insert_mode_p = True
        # Insert the record into the bibrec databases to have a recordId
        rec_id = create_new_record(pretend=pretend)
        write_message("   -Creation of a new record id (%d): DONE" % rec_id, verbose=2)

        # we add the record Id control field to the record
        error = record_add_field(record, '001', controlfield_value=rec_id)
        if error is None:
            msg = "   Failed: Error during adding the 001 controlfield "  \
                  "to the record"
            write_message(msg, verbose=1, stream=sys.stderr)
            return (1, int(rec_id), msg)
        else:
            error = None

        error = record_add_field(record, '005', controlfield_value=now.strftime("%Y%m%d%H%M%S.0"))
        if error is None:
            write_message("   Failed: Error during adding to 005 controlfield to record",verbose=1,stream=sys.stderr)
            return (1, int(rec_id))
        else:
            error=None

    elif opt_mode != 'insert' and opt_mode != 'format' and \
            opt_stage_to_start_from != 5:
        insert_mode_p = False
        # Update Mode
        # Retrieve the old record to update
        rec_old = get_record(rec_id)
        record_had_altered_bit = record_get_field_values(rec_old, CFG_BIBUPLOAD_EXTERNAL_OAIID_TAG[:3], CFG_BIBUPLOAD_EXTERNAL_OAIID_TAG[3], CFG_BIBUPLOAD_EXTERNAL_OAIID_TAG[4], CFG_OAI_PROVENANCE_ALTERED_SUBFIELD)
        # Also save a copy to restore previous situation in case of errors
        original_record = get_record(rec_id)

if 'contributors' in form and form['contributors']:
            fields = form.getlist('contributors')
            for f in fields:
                if f and not f.isspace():
                    record_add_field(rec, '700', subfields=[('a', remove_html_markup(f.strip()))])

        record_add_field(rec, '546', subfields=[('a', remove_html_markup(form['language']))])

        # copying zenodo here, but I don't think 980 is the right MARC field
        if 'resource_type' in form and form['resource_type']:
            fields = form.getlist('resource_type')
            for f in fields:
                record_add_field(rec, '980', subfields=[('a', remove_html_markup(form['resource_type']))])

        if 'alternate_identifier' in form and form['alternate_identifier']:
            record_add_field(rec, '024',
                             subfields=[('a', remove_html_markup(form['alternate_identifier']))])

        if 'version' in form and form['version']:
            record_add_field(rec, '250', subfields=[('a', remove_html_markup(form['version']))])
        record_add_field(rec, '264',
                         subfields=[('b', CFG_SITE_NAME),
                                    ('c', str(datetime.utcnow()) + " UTC")])
    except Exception as e:
        current_app.logger.error(e)
        raise

newval = ''
        if val[0] == 'OPEN':
            newval = 'open'
        elif val[0] == 'RESTRICTED':
            newval = 'restricted'
        elif val[0] == 'openAccess':
            newval = 'open'
        elif val[0] == 'closedAccess':
            newval = 'closed'
        elif val[0] == 'embargoedAccess':
            newval = 'embargoed'
        elif val[0] == 'restrictedAccess':
            newval = 'restricted'
        elif val[0] == 'cc0':
            newval = 'open'
            record_add_field(rec, '540', subfields=[('a', 'Creative Commons CCZero'), ('u', 'http://www.opendefinition.org/licenses/cc-zero')])
            record_add_field(rec, '650', ind1="1", ind2="7", subfields=[
                ('a', 'cc-zero'),
                ('2', 'opendefinition.org'),
            ])
        if newval:
            record_add_field(rec, '542', subfields=[('l', newval)])
            return (rec, newval)
        else:
            return (rec, val[0])
    return (rec, "closed")

record_delete_field(rec, '037', field_position_global=field[4])

    for field in record_get_field_instances(rec, '242'):
        record_add_field(rec, '246', subfields=field[0])
    record_delete_fields(rec, '242')

    # 269 Date normalization
    for field in record_get_field_instances(rec, '269'):
        for idx, (key, value) in enumerate(field[0]):
            if key == "c":
                field[0][idx] = ("c", convert_date_to_iso(value))
                record_delete_fields(rec, "260")

    if not 'THESIS' in collections:
        for field in record_get_field_instances(rec, '260'):
            record_add_field(rec, '269', subfields=field[0])
        record_delete_fields(rec, '260')

    # 300 page number
    for field in record_get_field_instances(rec, '300'):
        for idx, (key, value) in enumerate(field[0]):
            if key == 'a':
                if "mult." not in value and value != " p":
                    field[0][idx] = ('a', re.sub(r'[^\d-]+', '', value))
                else:
                    record_delete_field(rec, '300',
                                        field_position_global=field[4])
                    break

    # 100 & 700 punctuate author names
    author_names = record_get_field_instances(rec, '100')
    author_names.extend(record_get_field_instances(rec, '700'))