kata: make list of list as plain list of elements

solution1.py

#from functools import reduce # uncomment if python3+ is used
lmb = lambda x, y: x+reduce(lmb, y, []) if isinstance(y, list) else x + [y] 
reduce(lmb,[1,['a','b'],2,[[1,2, [3]]],'c'], [])

solution2.py

import functools

m = [1, ['a', 'b'], 2, [ [ 1, 2, [3]]], 'c']

def myreduce(x, y):
    if isinstance(y, list): return x + functools.reduce(myreduce, y, [])
    else: return x+[y]

functools.reduce(myreduce, m, [])