def file_diff(title, diff_data):
    """
    Builds a file diff element.  This element can be used to check whether
    configuration files have changed or other similar checks.  Differences
    will be highlighted when rendered via Javascript.

    Args:
        title: The title to display
        diff_data: A dictionary of the form:
            { 'section_name' : { 'variable_name' : [diff, val_1, val_2] } }

    Returns:
        A dictionary with the metadata specifying that it is to be
        rendered as a file diff element
    """
    fd = {
          'Type': 'Diff',
          'Title': title,
          'Data': diff_data,
          }
    return fd