events_by_year = {
1914: "World War I begins",
1918: "The end of World War I",
1939: "World War II begins",
1945: "The end of World War II",
}
# Looping from 1910 to 1914
for year in range(1900, 2000):
event = events_by_year.get(year)
if event is not None:
print(year, end=": ")
print(event)