anchor.diff:    postgresql_13 = self.callPackage generic {
       version = "13.7";
       psqlSchema = "13";
  -    sha256 = "sha256-G5Bb9PPYNhSjk7PFH9NFkQ/SYeT1Ekpo2aH906KkY5k=";
  +    hash = "sha256-G5Bb9PPYNhSjk7PFH9NFkQ/SYeT1Ekpo2aH906KkY5k=";
       this = self.postgresql_13;
       thisAttr = "postgresql_13";
       inherit self;
  
positive.code:   postgresql_11 = self.callPackage generic {
      version = "11.16";
      psqlSchema = "11.1"; # should be 11, but changing it is invasive
      sha256 = "sha256-LdnhEfCllJ7nyswGXOoPshCSkpuuMQzgW/AbT/xRA6U=";
      this = self.postgresql_11;
      thisAttr = "postgresql_11";
      inherit self;
  
negative.code:       , this, self, newScope, buildEnv
  
        # source specification
        , version, hash, psqlSchema,
  
        # for tests
        nixosTests, thisAttr
  