@staticmethod
def format_value(value):
    """Format value for rendering."""
    if isinstance(value, float):
        return '{0:.1f}'.format(value)
    if isinstance(value, int):
        return '{0}'.format(value)
    if value is None:
        return ''
    if hasattr(value, 'to_value'):
        return value.to_value()
    return value
