code: def lookup_document_pointer(ident_hash, cursor):
      
      id, version = split_ident_hash(ident_hash, split_version=True)
      stmt = "SELECT name FROM modules WHERE uuid = %s"
      args = [id]
      if version and version[0] is not None:
          operator = version[1] is None and 'is' or '='
          stmt += " AND (major_version = %s AND minor_version {} %s)" \
              .format(operator)
          args.extend(version)
      cursor.execute(stmt, args)
      try:
          title = cursor.fetchone()[0]
      except TypeError:
          raise DocumentLookupError()
      else:
          metadata = {'title': title}
      return cnxepub.DocumentPointer(ident_hash, metadata)
docs: Lookup a document by id and version.