Problem in flattening list

[Shahmadhur13]

I tried to flatten list.I have nested list and i want all iterables of that nested list in one list without any nested list. Itried with itertool.chain and also with recursive function.

import itertools

a = [[1,2,3], [4,7,8],9]
b = list(itertools.chain(a))
print(b)

def flatten(list):
	a=[]
	for i in list:
		if type(i) == list:
			flatten(i)
		else:
			a.append(i)
	return a
	
b =  [[1,2,3], [4,7,8],9]
c = flatten(b)
print(c)

I still get nested list in result. No changes