Python lists, modules, and loops (syntax error) -

currently learning python i'm little stumped particular question.

i need print length of list using loop without use of built-in functions.

i understand following works when input it:

listlength = 0  list1 = ['a', 'b', 'c', 'd']  y in list1:     listlength += 1 print(listlength) 

however question gives file cannot edit:

import function_lists  list1 = ['a', 'b', 'c', 'd']  print("length of list:", function_lists.listlength(list1)) 

in editable file named function_lists i've done this:

def length(a_list)      length = 0      y in list1:         listlength += 1 

syntax error: list1 not defined - can tell i'm misunderstanding how modules work, shouldn't list1 pulled out of un-editable file via import function_lists work?

i'd ask prac tutor don't have until late week.

you should using parameter name, a_list, instead of parameter passed, list1. @andy g pointed out, when declaring functions, need end declaration colon(eg. def function_name(args):). moreover, default return value of function none so, @riad pointed out, should return length variable.

def length(a_list)      length = 0      y in list1:         listlength += 1 

should be

def length(a_list):     length = 0     y in a_list:         length += 1     return length