code: function getCompetitors (keyword, apps) {
      return Promise.all(apps.map((app) => isCompetitor(keyword, app)))
        .then(R.filter(R.identity))
        .then(R.length)
        .then((count) => ({count, score: calc.zScore(apps.length, count)}));
    }
docs: /*
  Score the amount apps that have the keyword as one of their top keywords in
  their description.