code: function getContentType(file) {
    var mimeType =
      mime.lookup(file.unzipPath || file.path) || 'application/octet-stream';
    var charset = mime.charset(mimeType);
  
    return charset ? mimeType + '; charset=' + charset.toLowerCase() : mimeType;
  }
docs: Determine the content type of a file based on charset and mime type.
  @param  {Object} file
  @return {String}
  
  @api private