def subsetDf(data_input):
    """
    Take a DataFrame and if it's under 500 unique objects, simply return it. 
    If the DataFrame is over 500 unique objects, return the first 
    500 unique objects. 
    """
    unique_obj = data_input.index.unique()
    unique_obj_list = list(unique_obj)
    if len(unique_obj) <= 500:
        return data_input
    else:
        first500 = unique_obj_list[0:500]
        data_input = data_input[data_input.index.isin(first500)]
        return data_input