flaten a python nested list code example

Example 1: flatten a list of lists python

flattened = [val for sublist in list_of_lists for val in sublist]

Example 2: python nested list

L = [[1, 2, 3],[4, 5, 6],[7, 8, 9]]   
for list in L:
    for number in list:
        print(number, end=' ')
# Prints 1 2 3 4 5 6 7 8 9