def import_optional(mod_name):
    ''' Attempt to import an optional dependency.

    Silently returns None if the requested module is not available.

    Args:
        mod_name (str) : name of the optional module to try to import

    Returns:
        imported module or None, if import fails

    '''
    try:
        return import_module(mod_name)
    except __HOLE__:
        return None
dataset/ETHPy150Open bokeh/bokeh/bokeh/util/dependencies.py/import_optional