Python Syntax for "If X != A, B or C"

Question

I'm a little stuck at trying to figure out this python syntax (I know is going to be a super simple fix too). What I want to do is say

if unit is not g, ml, or kg then return a flag. I tried:

if unit != ('g' or 'ml' or 'kg'):
return 1

If unit is set to g, the program doesn't return 1

If unit is set to ml, or kg, the program returns 1.

How do I make it so I can simply, and clearly say to return 1 if unit is not g, ml, or kg?

edit: I know I can do

if unit != 'g':
if unit != 'ml':
if unit != 'kg':
return 1

but this is 3 lines of code where I think 1 line can solve it.

Answer 1

Note: You can't return a value from an if statement, you can only return a value from a function.

I would create a list of the units:

units = ['g','ml','kg']

Then test if the unit is in the list or not.

unit = 'g'
if unit in units:
    print(True)
else:
    print(False)