add all items in list to another list python

# Basic syntax:
first_list.append(second_list) # Append adds the the second_list as an
#	element to the first_list
first_list.extend(second_list) # Extend combines the elements of the 
#	first_list and the second_list

# Note, both append and extend modify the first_list in place

# Example usage:
first_list = [1, 2, 3, 4, 5]
second_list = [6, 7, 8, 9]
first_list.append(second_list)
print(first_list)
--> [1, 2, 3, 4, 5, [6, 7, 8, 9]]

# Example usage:
first_list = [1, 2, 3, 4, 5]
second_list = [6, 7, 8, 9]
first_list.extent(second_list)
print(first_list)
--> [1, 2, 3, 4, 5, 6, 7, 8, 9]

a = [1, 2, 3]
b = [4, 5, 6]
a += b
# another way: a.extend(b)

a = [1]
b = [2,3]
a.extend(b)
print(a)

------  OR  -------
a += b