code: def get_nodesitemtypeinsertion(cls, itemgroup, indent) -> str:
          
          blanks = ' ' * (indent * 4)
          subs = [
              f'{blanks}<complexType name="nodes_{itemgroup}Type">',
              f'{blanks}    <sequence>',
              f'{blanks}        <element ref="hpcb:selections"',
              f'{blanks}                 minOccurs="0"/>',
              f'{blanks}        <element ref="hpcb:devices"',
              f'{blanks}                 minOccurs="0"/>']
          type_ = 'getitemType' if itemgroup == 'getitems' else 'setitemType'
          for name in ('sim', 'obs', 'sim.series', 'obs.series'):
              subs.extend([
                  f'{blanks}        <element name="{name}"',
                  f'{blanks}                 type="hpcb:{type_}"',
                  f'{blanks}                 minOccurs="0"',
                  f'{blanks}                 maxOccurs="unbounded"/>'])
          subs.extend([
              f'{blanks}    </sequence>',
              f'{blanks}</complexType>',
              f''])
          return '\n'.join(subs)
docs: Return a string defining the required types for the given
          combination of an exchange item group and |Node| objects.
  
          >>> from hydpy.auxs.xmltools import XSDWriter
          >>> print(XSDWriter.get_nodesitemtypeinsertion(
          ...     'setitems', 1))    # doctest: +ELLIPSIS
              <complexType name="nodes_setitemsType">
                  <sequence>
                      <element ref="hpcb:selections"
                               minOccurs="0"/>
                      <element ref="hpcb:devices"
                               minOccurs="0"/>
                      <element name="sim"
                               type="hpcb:setitemType"
                               minOccurs="0"
                               maxOccurs="unbounded"/>
                      <element name="obs"
                               type="hpcb:setitemType"
                               minOccurs="0"
                               maxOccurs="unbounded"/>
                      <element name="sim.series"
                               type="hpcb:setitemType"
                               minOccurs="0"
                               maxOccurs="unbounded"/>
                      <element name="obs.series"
                               type="hpcb:setitemType"
                               minOccurs="0"
                               maxOccurs="unbounded"/>
                  </sequence>
              </complexType>
          <BLANKLINE>