Python Bandit -equivalent of fromstring in defusedxml.ElementTree?

I am trying to read xml file from S3 location and using diffusedxml library. Code executes fine, but Bandit throws medium Severity in code analysis and throws following message-

blacklist: Using lxml.etree.parse to parse untrusted XML data is known to be vulnerable to XML attacks. Replace lxml.etree.parse with its defusedxml equivalent function. Test ID: B320 Severity: MEDIUM Confidence: HIGH CWE: CWE-20 File: ./lambda_code/ccda_step2_validation/defusedxml/defusedxml/lxml.py Line number: 135 More info: https://bandit.readthedocs.io/en/1.7.4/blacklists/blacklist_calls.html#b313-b320-xml-bad-etree 134 parser = getDefaultParser() 135 elementtree = _etree.parse(source, parser, base_url=base_url) 136 check_docinfo(elementtree, forbid_dtd, forbid_entities) blacklist: Using lxml.etree.fromstring to parse untrusted XML data is known to be vulnerable to XML attacks. Replace lxml.etree.fromstring with its defusedxml equivalent function. Test ID: B320 Severity: MEDIUM Confidence: HIGH CWE: CWE-20 File: ./lambda_code/ccda_step2_validation/defusedxml/defusedxml/lxml.py Line number: 143 More info: https://bandit.readthedocs.io/en/1.7.4/blacklists/blacklist_calls.html#b313-b320-xml-bad-etree 142 parser = getDefaultParser() 143 rootelement = _etree.fromstring(text, parser, base_url=base_url) 144 elementtree = rootelement.getroottree()

Here is my Pseudo code

from defusedxml.defusedxml.ElementTree import fromstring
is_valid_file = False
S3_CLIENT = boto3.client("s3")
s3_file = S3_CLIENT.get_object(Bucket=bucketname, Key=filename_with_key)
                    #Read a text file entire content 
                    s3_filedata = s3_file["Body"].read()
                    try:
                        #tree = ET.ElementTree(ET.fromstring(s3_filedata))
                        tree = fromstring(s3_filedata)
                        #search_document_header = tree.getroot()
                        search_document_header = tree.findall(".")
                        search_patient_section = tree.findall(".//{urn:hl7-org:v3}patientRole")                        
                        if str(search_document_header).find("ClinicalDocument") !=-1 and str(search_patient_section).find("patientRole") !=-1:
                            is_valid_file = True
                    except Exception as e:                         
                        is_valid_file = False
                        LOGGER.error("in parse error")