flatten list of list through list comprehension

Question

I am trying to flatten a list using list comprehension in python. My list is somewhat like

[[1, 2, 3], [4, 5, 6], 7, 8]

just for printing

Answer 1

def nnl(nl):    # non nested list

    nn = []

    for x in nl:
        if type(x) == type(5):
            nn.append(x)

    if type(x) == type([]):
        n = nnl(x)

        for y in n:
            nn.append(y)
    return nn

print (nnl([[9, 4, 5], [3, 8,[5]], 6]))  # output: [9, 4, 5, 3, 8, 5, 6]