code: def fix_missing_electronic_locator_tag(dom, url):
      
      electronic_locator = dom.match(
          "mods:mods",
          "mods:location",
          "mods:holdingSimple",
          "mods:copyInformation",
          "mods:electronicLocator",
      )
      # do not try to fix correct records
      if electronic_locator:
          return
  
      # if no location tag found, add it
      location = dom.match("mods:mods", "mods:location")
      if location:
          location = first(location)
      else:
          location_tag = dhtmlparser.parseString(
              "<mods:location></mods:location>"
          )
  
          insert_tag(
              location_tag,
              dom.find("mods:recordInfo"),
              get_mods_tag(dom)
          )
  
          location = first(dom.match("mods:mods", "mods:location"))
  
      replacer = dhtmlparser.parseString("""
    <mods:location>
      <mods:holdingSimple>
        <mods:copyInformation>
          <mods:electronicLocator>""" + url + """</mods:electronicLocator>
        </mods:copyInformation>
      </mods:holdingSimple>
    </mods:location>
      """)
  
      location.replaceWith(
          first(replacer.find("mods:location"))
      )
docs: In case that MODS contains no URL and the location is wrong (physical), add
      url from `url` parameter.