function runRegexOnDoc(re, host){
    // @re regex that has a submatch in it that we're searching for, like /foo(.+?)bar/
    // @host optional. only work on this host.

    if (!host || host == myHost){
        var m = re.exec(docAsStr)
        if (m && m.length > 1){
            return m[1]
        }
    }
    return false
}
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 Page scraping functions, for DOIs and PDF links

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