code: def get_itemtypesinsertion(cls, itemgroup, indent) -> str:
          
          subs = []
          for modelname in cls.get_modelnames():
              subs.append(cls.get_itemtypeinsertion(itemgroup, modelname, indent))
          subs.append(cls.get_nodesitemtypeinsertion(itemgroup, indent))
          return '\n'.join(subs)
docs: Return a string defining the required types for the given
          exchange item group.
  
          >>> from hydpy.auxs.xmltools import XSDWriter
          >>> print(XSDWriter.get_itemtypesinsertion(
          ...     'setitems', 1))    # doctest: +ELLIPSIS
              <complexType name="arma_v1_setitemsType">
          ...
              </complexType>
          <BLANKLINE>
              <complexType name="dam_v001_setitemsType">
          ...
              <complexType name="nodes_setitemsType">
          ...