code: function getDestinationDir(vFile) {
    if (vFile.data.destinationDir) {
      return vFile.data.destinationDir;
    }
  
    return vFile.dirname;
  }
docs: Returns the destination for the SVG to be rendered at, explicity defined
  using `vFile.data.destinationDir`, or falling back to the file's current
  directory.
  
  @param {vFile} vFile
  @return {string}