Contract: It is an agreement between the parties to establish, modify, and terminate civil relations. A contract established in accordance with the law is protected by law. The establishment of a contract must follow two principles: 1. the principle of legality; 2. the principle of equality and mutual benefit, consensus, and equal compensation.
Before committing the crime, two thieves made a life-and-death agreement. Once one of the two persons is caught, the second person must never be confessed is not part of a contract according to the above definition.