Return MESH headings for articles

[brandonStell]

For each DOI there are a series of keywords, called MESH headings in the pubmed (eutils) metadata.

e.g.
DOI: 10.1038/s41419-017-0128-y
Note that the keywords are not in the crossref data:

curl -D - -L -H   "Accept: application/unixref+xml" "https://doi.org/10.1038/s41419-017-0128-y"

But they are in the eutils data under the <MeshHeading> tag:
https://www.ncbi.nlm.nih.gov/pubmed/?term=Transmembrane+protein+170B+is+a+novel+breast+tumorigenesis+suppressor+gene+that+inhibits+the+Wnt&report=xml&format=text

[brandonStell]

we could use the existing tags table to hold the keywords.

I guess the code for it would be here:
https://github.com/PubPeerFoundation/PublicationDataExtractor/blob/master/src/Resources/Extractors/EutilsEfetch.php

here is a total guess for what the code might look like:

 public function extractTagsData(): void
    {
        foreach ($this->searchTree->PubmedData->MeshHeadingList->MeshHeading->DescriptorName as $tag) {
            $this->resourceOutput['tags'] = [
                'value' => (string) $tag
           ];
        }