products = [{'product':'product1'},{'product':'product2'},{'product':'product3'},{'product':'product4'}]

sales = [{'sale':'sale1'},{'sale':'sale2'}]

invoices = [{'invoice':'invoice1'},{'invoice': 'invoice2'},{'invoice':'invoice3'}]

combination_list = [
    {'product':'product1', 'sale':'sale1','invoice':'invoice1'},
    {'product':'product2', 'sale':'sale1','invoice':'invoice1'},
    {'product':'product3', 'sale':'sale1','invoice':'invoice1'},
    {'product':'product3', 'sale':'sale2','invoice':'invoice1'},
    {'product':'product3', 'sale':'sale3','invoice':'invoice1'},
.
.
.
.
    ]