Concatenate strings

string_concat.py

### Concatenate string using '+' operation
def add_string_with_plus(iters):
    s = ""
    for i in range(iters):
        s += "abc"
    assert len(s) == 3*iters
    
### Concatenate strings using join() function
def add_string_with_join(iters):
    l = []
    for i in range(iters):
        l.append("abc")
    s = "".join(l)
    assert len(s) == 3*iters
    
### Compare speed
>>> timeit(add_string_with_plus(10000))
100 loops, best of 5: 3.74 ms per loop
>>> timeit(add_string_with_join(10000))
100 loops, best of 5: 2.3 ms per loop