timings for a is_mixed_case(string) function

test.py

from timeit import timeit

name = 'common_case'

def f0(name):  # 0.38833552993028425
    stripped_name = name.strip('_')
    tail = stripped_name[1:]
    return stripped_name[:1].islower() and tail.lower() != tail

def f1(name):  # 0.5023811628120246
    stripped_name = name.strip('_')
    head = stripped_name[:1]
    tail = stripped_name[1:]
    return head.islower() and bool(tail) and not (tail.islower() or tail.isdigit())

def f2(name):  # 1.2597934653988185
    stripped_name = name.strip('_')
    head_is_lower = stripped_name[:1].islower()
    return head_is_lower and any(map(str.isupper, stripped_name[1:]))

def f3(name):  # 1.399307801830291
    stripped_name = name.strip('_')
    head_is_lower = stripped_name[:1].islower()
    return head_is_lower and any(c.isupper() for c in stripped_name[1:])

def f4(name):  # 0.9169683581987003
    stripped_name = name.strip('_')
    if stripped_name[:1].islower():
        for c in stripped_name:
            if c.isupper():
                return True

def f5(name):  # 0.37668225294656565
    stripped_name = name.lstrip('_')
    tail = stripped_name[1:]
    return stripped_name[:1].islower() and tail.lower() != tail


def f6(name):  # 0.32481864568646446
    return name.lstrip('_')[:1].islower() and name.lower() != name


print(timeit('f0(name)', globals=globals()))
print(timeit('f1(name)', globals=globals()))
print(timeit('f2(name)', globals=globals()))
print(timeit('f3(name)', globals=globals()))
print(timeit('f4(name)', globals=globals()))
print(timeit('f5(name)', globals=globals()))
print(timeit('f6(name)', globals=globals()))