What is the accounts receivable, net increase / (decrease) from 2018 to 2019?
{"Accounts receivable, net": {"2019": 120016, "2018": 133136}, "Contract assets": {"2019": 18804, "2018": 12128}, "Contract liabilities": {"2019": 50974, "2018": 52966}}
accounts_receivable_net_2019 = df["Accounts receivable, net"]["2019"]
accounts_receivable_net_2018 = df["Accounts receivable, net"]["2018"]
answer = accounts_receivable_net_2019 - accounts_receivable_net_2018