how to merge to list in pyhton code example

Example 1: python how to add one list to another list

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

Example 2: merge lists in list python

import itertools
a = [['a','b'], ['c']]
print(list(itertools.chain.from_iterable(a)))