from typing import List
from typing import Tuple
from datetime import datetime


def average_of_all(data: List[Tuple[datetime, float]]) -> float:
    """
    Return average sentiment of a list of tweet sentiments
    >>> average_of_all([(datetime(2020, 12, 11), 2.0), \
    (datetime(2020, 12, 11), 4.0), (datetime(2020, 12, 12), 3.0)])
    3.0
    """
    sum_value = 0
    for value in data:
        sum_value += value[1]
    return sum_value / len(data)