import io
import lxml.etree as ET
content = """<Envelope xmlns="http://www.example.com/zzz/yyy">
  <Header>
    <Version>1</Version>
  </Header>
  <Body>
    some stuff
  </Body>
</Envelope>
"""
dom = ET.parse(io.BytesIO(content))
lxml etree xmlparser remove unwanted namespace