What I did

What I learned

def test1():
    l = []
    for i in range(1000):
        l = l + [i]

def test2():
    l = []
    for i in range(1000):
        l.append(i)

def test3():
    l = [i for i in range(1000)]

def test4():
    l = list(range(1000))

t1 = Timer("test1()", "from __main__ import test1")
print("concat ", t1.timeit(number=1000), "milliseconds")
t2 ... t4 = ...

---output---
concat  6.54352807999 milliseconds
append  0.306292057037 milliseconds
comprehension  0.147661924362 milliseconds
list range  0.0655000209808 milliseconds
find . -name "*.Identifier" -type f -delete

What I will do next