join list of lists in python

If you're only going one level deep, a nested comprehension will also work:

>>> x = [["a","b"], ["c"]]
>>> [inner
...     for outer in x
...         for inner in outer]
['a', 'b', 'c']

On one line, that becomes:

>>> [j for i in x for j in i]
['a', 'b', 'c']

x = [["a","b"], ["c"]]

result = sum(x, [])

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

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