title: Example of fill bgColor cell in excel4node
body: <p>I am using excel4node to create Excel file in nodeJS.
  The site gives following guideline to use fill property.</p>
  
  <pre><code>fill: { // §18.8.20 fill (Fill)
        type: string, // Currently only 'pattern' is implimented. Non-   implimented option is 'gradient'
        patternType: string, //§18.18.55 ST_PatternType (Pattern Type)
        bgColor: string // HTML style hex value. optional. defaults to black
        fgColor: string // HTML style hex value. required.
    },
  </code></pre>
  
  <p>I could not work around this.  Anyone can help me, please?</p>