membership.py

from xml.etree import ElementTree
from xml.etree.ElementTree import Element
from xml.etree.ElementTree import SubElement

# <membership/>
membership = Element( 'membership' )

# <membership><users/>
users = SubElement( membership, 'users' )

# <membership><users><user/>
SubElement( users, 'user', name='john' )
SubElement( users, 'user', name='charles' )
SubElement( users, 'user', name='peter' )

# <membership><groups/>
groups = SubElement( membership, 'groups' )

# <membership><groups><group/>
group = SubElement( groups, 'group', name='users' )

# <membership><groups><group><user/>
SubElement( group, 'user', name='john' )
SubElement( group, 'user', name='charles' )

# <membership><groups><group/>
group = SubElement( groups, 'group', name='administrators' )

# <membership><groups><group><user/>
SubElement( group, 'user', name='peter' )