Django custom file syntax error -

i syntax error in cart.py file created in 'cart' app basic cart functions

if cart_item.menuitem.id = i.id:

cart.py:

# add item cart def add_to_cart(request):     postdata = request.post.copy()     # menuitem slug post data, return blank if empty     menuitem_slug = postdata.get('menuitem_slug','')     # quantity added, return 1 if empty     quantity = postdata.get('quantity',1)     # fetch menuitem or return missing page error     = get_object_or_404(menuitem, slug=menuitem_slug)     #get menuitems in cart     cart_menuitems = get_cart_items(request)     menuitem_in_cart = false     # check see if item in cart     cart_item in cart_menuitems:         if cart_item.menuitem.id = i.id:             # update quantity if found             cart_item.augment_quantity(quantity)             product_in_cart = true     if not product_in_cart:         # create , save new cart item         ci = cartitem()         ci.menuitem =         ci.quantity = quantity         ci.cart_id = _cart_id(request)         ci.save()   # returns total number of items in user's cart def cart_distinct_item_count(request):     return get_cart_items(request).count()  

are assigning value?? or checking it??

change line

if cart_item.menuitem.id = i.id: 

to

if cart_item.menuitem.id == i.id: