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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_itemsinsertion(cls, itemgroup, indent) -> str: """Return a string defining the XML element for the given exchange item group. <element name="setitems"> <complexType> <sequence> <element ref="hpcb:selections" minOccurs="0"/> <element ref="hpcb:devices" minOccurs="0"/> <element name="hland_v1" type="hpcb:hland_v1_setitemsType" minOccurs="0" maxOccurs="unbounded"/> <element name="nodes" type="hpcb:nodes_setitemsType" minOccurs="0" maxOccurs="unbounded"/> </sequence> <attribute name="info" type="string"/> </complexType> </element> <BLANKLINE> """

        blanks = ' ' * (indent*4)
        subs = []
        subs.extend([
            f'{blanks}<element name="{itemgroup}">',
            f'{blanks}    <complexType>',
            f'{blanks}        <sequence>',
            f'{blanks}            <element ref="hpcb:selections"',
            f'{blanks}                     minOccurs="0"/>',
            f'{blanks}            <element ref="hpcb:devices"',
            f'{blanks}                     minOccurs="0"/>'])
        for modelname in cls.get_modelnames():
            type_ = cls._get_itemstype(modelname, itemgroup)
            subs.append(f'{blanks}            <element name="{modelname}"')
            subs.append(f'{blanks}                     type="hpcb:{type_}"')
            subs.append(f'{blanks}                     minOccurs="0"')
            subs.append(f'{blanks}                     maxOccurs="unbounded"/>')
        if itemgroup in ('setitems', 'getitems'):
            type_ = f'nodes_{itemgroup}Type'
            subs.append(f'{blanks}            <element name="nodes"')
            subs.append(f'{blanks}                     type="hpcb:{type_}"')
            subs.append(f'{blanks}                     minOccurs="0"')
            subs.append(f'{blanks}                     maxOccurs="unbounded"/>')
        subs.extend([
                f'{blanks}        </sequence>',
                f'{blanks}        <attribute name="info" type="string"/>',
                f'{blanks}    </complexType>',
                f'{blanks}</element>',
                f''])
        return '\n'.join(subs)