def train_test_split(df, frac):
    """
    Create a Train/Test split function for a dataframe and return both 
    the Training and Testing sets.
    Frac refers to the percent of data you would like to set aside
    for training.
    """
    frac = round(len(df)*frac)
    train = df[:frac]
    test = df[frac:]

    return train, test