In [1]: def sum10(l):
   ...:     from itertools import accumulate
   ...:     return list(accumulate(reversed(l)))[::-1]+[l[0]]
   ...:
   ...: def sum11(l):
   ...:     from itertools import accumulate
   ...:     return list(accumulate(l[::-1]))[::-1]+[l[0]]
   ...:
   ...:
   ...: def sum20(l):
   ...:     from numpy import cumsum
   ...:     return list(cumsum(l[::-1]))[::-1]+[l[0]]
   ...:
   ...: def sum21(l):
   ...:     from numpy import cumsum
   ...:     return list(cumsum(reversed(l)))[::-1]+[l[0]]
   ...:

In [2]: %timeit(sum10)
UsageError: Line magic function `%timeit(sum10)` not found.

In [3]: %timeit sum10
21.2 ns ± 0.0116 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [4]: %timeit sum11
21.1 ns ± 0.0225 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [5]: %timeit sum20
25.3 ns ± 0.098 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [6]: %timeit sum21
23.5 ns ± 0.0137 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)