combining list of list to single list python

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

Here is what the above code is Doing:
1. itertools.chain.from_iterable(a)
2. itertools.chain(a[0], a[1])
3. itertools.chain([‘a’,’b’], [‘c’])
4. [‘a’,’b’,’c’]