error:
       … while evaluating a
         at /pwd/in.nix:1:84:
            1| let b = builtins.toJSON a; a = { foo = "bar"; "${builtins.seq b "baz"}" = b; }; in a
             |                                                                                    ^
            2|

       … while calling the 'seq' builtin
         at /pwd/in.nix:1:50:
            1| let b = builtins.toJSON a; a = { foo = "bar"; "${builtins.seq b "baz"}" = b; }; in a
             |                                                  ^
            2|

       … while calling the 'toJSON' builtin
         at /pwd/in.nix:1:9:
            1| let b = builtins.toJSON a; a = { foo = "bar"; "${builtins.seq b "baz"}" = b; }; in a
             |         ^
            2|

       error: infinite recursion encountered