2 for and 1 if in list comprehension code example

Example 1: python list comprehension

#example: removing common elements found in `a` from `b`.
a = [1,2,3,4,5]
b = [5,6,7,8,9]
# desired output: [1,2,3,4]

# gets each item found in `a` AND not in `b`
print([i for i in a if i not in b])

Example 2: nested loop in list comprehension

# 2-D List 
matrix = [[1, 2, 3], [4, 5], [6, 7, 8, 9]] 
  
# Nested List Comprehension to flatten a given 2-D matrix 
flatten_matrix = [val for sublist in matrix for val in sublist] 
  
print(flatten_matrix)