python - why [].append(1) is None -

this question has answer here:

i use python this

>>>print [].append(1) none  >>>ls = [] >>>ls.append(1) >>>ls [1]

why "[].append(1)" value none ,and other 1 real value?

because append() list method doesn't return list, modifies list called on. in case, anonymous list modified , thrown away.

the documentation isn't super-clear, says is:

list.append(x)

add item end of list; equivalent a[len(a):] = [x].

for other methods, such list.count(x), word "return" occurs in description, implying if doesn't, method doesn't have return value.

Brazell