def kill_duplicates(df):
    """
    Remove duplicate entries from a DataFrame (keeps the first one).
    """
    old_count = df.shape[0]
    new_df = df.loc[~df.duplicated()]
    new_count = new_df.shape[0]
    if new_count <= old_count:
        print('Removed {} of {} duplicate index entries, {} remaining'.
            format(old_count - new_count, old_count, new_count))
    return new_df
