def calculate_avg_length(self, data_df):
    num = data_df.shape[0]
    content_list = data_df.content.sum()
    print((len(content_list) / num))
def calculate_avg_length(self, data_df):
    num = data_df.shape[0]
    content_list = data_df.content.sum()
    print((len(content_list) / num))