code: function splitPagesPromise (content) {
      var pages = content.split(/\f/)
      if (!pages) {
        var ex = {
          message: 'pdf-text-extract failed',
          error: 'no text returned from the pdftotext command',
          filePath: this.filePath,
          stack: new Error().stack
        }
        throw ex
      }
      // sometimes there can be an extract blank page on the end
      var lastPage = pages[pages.length - 1]
      if (!lastPage) {
        pages.pop()
      }
      resolve(pages)
    }
docs: Duplicated from function splitPages of pdfTextExtract