align-items or align-self properties is not reconized as a property, when justify-content is. I’m using the sass package

and when I explore the code, these properties are in the package code.
PROPERTY_DICT = {
'align-items': ['baseline', 'center', 'flex-end', 'flex-start', 'stretch'],
...
'justify-content': [
'start', 'end', 'flex-start', 'flex-end', 'center', 'left', 'right',
'safe start', 'safe end', 'safe flex-start', 'safe flex-end',
'safe center', 'safe left', 'safe right', 'unsafe start',
'unsafe end', 'unsafe flex-start', 'unsafe flex-end', 'unsafe center',
'unsafe left', 'unsafe right', 'normal', 'baseline', 'first baseline',
'last baseline', 'space-between', 'space-around', 'space-evenly',
'stretch'
],
Why one and not the other?
