new.py

## based on airbnb proto interview

def rev(s):
    return s[::-1]

# a .. b
# (a,b) .. (b,a)
def mir(a,b):
    i = a
    j = b
    while i <= b and j >= a:
        yield (i,j)
        i += 1
        j -= 1

# a .. b
# (a,b) .. (b,a)
def mig(a,b):
    i = a
    j = b
    while i < j:
        yield (i,j)
        i += 1
        j -= 1
    yield (i,j)

def rev_(s):
    if s:
        l = len(s)
        o = bytearray(l)
        for (i,j) in mig(0,l-1):
            o[j] = ord(s[i])
            o[i] = ord(s[j])
        return o.decode()
    else:
        return s