lib/modifiers/summary/insertPart.js
function insertPart(summary, part, index) {
    part = SummaryPart(part);

    var parts = summary.getParts().insert(index, part);
    return indexLevels(summary.set('parts', parts));
}
function insertPart(summary, part, index) {
    part = SummaryPart(part);

    var parts = summary.getParts().insert(index, part);
    return indexLevels(summary.set('parts', parts));
}
function insertPart ( summary , part , index ) { part = SummaryPart ( part ) ; var parts = summary . getParts ( ) . insert ( index , part ) ; return indexLevels ( summary . set ( 'parts' , parts ) ) ; }
Returns a new Summary with a part inserted at given index

@param {Summary} summary
@param {Part} part
@param {Number} index
@return {Summary}
Returns a new Summary with a part inserted at given index