Remove exception implying map or filter are ever acceptable

[graingert]

thankfully we now have black so multiline comprehensions are beautiful

[graingert]

@adewes ^

[graingert]

perhaps a note to extract processing that requires multiple statements into a function:

Extract expressions that are too long or complicated to express directly within a list comprehension into a function:

def process(v):
    if v.ham == "spam":
        return 4
    if v.bacon == "eggs"
        return 7
    ...

def cond(v):
    ...

[process(x) for x in items if cond(v)]  # still preferable to map(process, filter(cond, items))