def METHOD_NAME(self, proposal):
    """Strip 'fa-' if necessary'"""
    value = proposal['value']
    if 'fa-' in value:
        deprecation("icons names no longer need 'fa-', "
        "just use the class names themselves (for example, 'gear spin' instead of 'fa-gear fa-spin')",
        internal=['ipywidgets/widgets/', 'traitlets/traitlets.py', '/contextlib.py'])
        value = value.replace('fa-', '')
    return value