#A function is "consistent" if it always returns the same value for the same arguments.
#A function can be consistent even if it is not:
# - deterministic
# - free of side effects
#That said, "F is deterministic and F is free of side effects" does imply "F is consistent"

#consistent, deterministic, no side effects
def a(x):
    return x * 2

#consistent, deterministic, has side effects
_cache = []
def b(x):
    _cache.append(x)
    return x

#consistent, not deterministic, no side effects
#(pointless, yes, but still possible)
def c(x):
    if true_random.choice((False, True)):
        return x
    else:
        return x

#consistent, not deterministic, side effects
_cache = []
def d(x):
    _cache.append(x * true_random.random())
    return x

#not consistent, deterministic, no side effects
def e(x):
    #... Pretty sure this one is impossible actually
    pass

#not consistent, deterministic, has side effects
_cache = []
def f(x):
    _cache.append(x)
    return len(_cache)

#not consistent, not deterministic, no side effects
def g(x):
    return x * true_random.random()

#not consistent, not deterministic, has side effects
_cache = []
def h(x):
    _cache.append(x * true_random.random())
    return len(_cache)