Hi, I am trying to remove 2019 and add 2020. But it doesn't give me results unless I go in and run each 'deleted_head()' or 'add_year(). I want to get it to run and give the new result ['happy christmas', 'lets eat', 2020]

a = [2019, 'happy christmas', 'lets eat']

def delete_head():

del a[0]

def add_year():

a.append(2020)

print (a)