incparsexml.py

from collections import deque
from io import BytesIO
from lxml import etree

istr = BytesIO(b"""<object class="EnumDnSched">
  <field name="enumDn">
    <value>343741014</value>
  </field>
  <field name="naptrFlags">
    <value>nu</value>
  </field>
</object>
<object class="EnumDnSched">
  <field name="enumDn">
    <value>343741015</value>
  </field>
  <field name="naptrFlags">
    <value>nu</value>
  </field>
</object>""")

events = etree.iterparse(istr, events=("start", "end"))
stack = deque()
for event, element in events:
    if event == "start":
      stack.append(element)
    elif event == "end":
      stack.pop()

    if len(stack) == 0:
      break

    print(istr.tell(), "%5s, %4s, %s" % (event, element.tag, element.text))

try:
  next(events)
except Exception as e:
  print(e.args)
  print(e.offset)

output

327 start, object, 
  
327 start, field, 
    
327 start, value, 343741014
327   end, value, 343741014
327   end, field, 
    
327 start, field, 
    
327 start, value, nu
327   end, value, nu
327   end, field, 
    
('Extra content at the end of the document, line 9, column 1',)
None