You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: _MeasureEnsemblePF_BxPP_Nodes.gen.m
    path of file: ./repos/BRAPH-2/braph2genesis/src/analysis
    
    the code of the file until where you have to start completion: %% ¡header!
MeasureEnsemblePF_BxPP_Nodes < PanelProp (pr, nodes prop panel) plots the panel to select a couple of nodes.

%%% ¡description!
A Nodes Prop Panel (MeasureEnsemblePF_BxPP_Nodes) plots the panel to select the nodes from two drop-down lists.
It is supposed to be used with the property NODES of MeasureEnsemblePF_BU, MeasureEnsemblePF_BS, or MeasureEnsemblePF_BB.

%%% ¡seealso!
uidropdown, GUI, Measure
    
function cb_dropdown_node(~, ~)
    pr.get('EL').set(pr.get('PROP'), [get(pr.get('DROPDOWN_NODE1'), 'Value') get(pr.get('DROPDOWN_NODE2'), 'Value')])
end

%%% ¡prop!
DROPDOWN_NODE2 (evanescent, handle) is the dropdown for the second node.
%%%% ¡calculate!
el = pr.get('EL');
prop = pr.get('PROP');

dropdown = uidropdown( ...
    'Parent', pr.memorize('H'), ... % H = p for Panel
    'Tag', 'DROPDOWN_NODE2', ...
    'FontSize', BRAPH2.FONTSIZE, ...
    'Tooltip', [num2str(el.getPropProp(prop)) ' ' el.getPropDescription(prop)], ...
    'ValueChangedFcn', {@cb_dropdown_node} ...
    );

value = dropdown;
%%%% ¡calculate_callbacks!
function cb_dropdown_node2(~, ~)
    pr.get('EL').set(pr.get('PROP'), [get(pr.get('DROPDOWN_NODE1'), 'Value') get(pr.get('DROPDOWN_NODE2'), 'Value')])
end