anchor.diff:  
     # Cirq 0.6 requires networkx==2.3 only for optional qiskit dependency/test, disable this to avoid networkx version conflicts. https://github.com/quantumlib/Cirq/issues/2368
     # Cirq locks protobuf==3.8.0, but tested working with default pythonPackages.protobuf (3.7). This avoids overrides/pythonPackages.protobuf conflicts
  -  prePatch = ''
  +  postPatch = ''
       substituteInPlace requirements.txt --replace "networkx==2.3" "networkx" \
         --replace "protobuf==3.8.0" "protobuf"
   
       # Fix sympy 1.5 test failures. Should be fixed in v0.7
       substituteInPlace cirq/optimizers/eject_phased_paulis_test.py --replace "phase_exponent=0.125 + x / 8" "phase_exponent=0.125 + x * 0.125"
       substituteInPlace cirq/contrib/quirk/cells/parse_test.py --replace "parse_formula('5t') == 5 * t" "parse_formula('5t') == 5.0 * t"
  +
  +    # Fix pandas >= 1.0 error, #2886
  +    substituteInPlace cirq/experiments/t1_decay_experiment.py --replace "del tab.columns.name" 'tab.rename_axis(None, axis="columns", inplace=True)'
     '';
   
     propagatedBuildInputs = [
  
positive.code:     "--ignore=dev_tools"  # Only needed when developing new code, which is out-of-scope
      "--ignore=cirq/google/op_serializer_test.py"  # investigating in https://github.com/quantumlib/Cirq/issues/2727
    ];
  
    meta = with lib; {
      description = "A framework for creating, editing, and invoking Noisy Intermediate Scale Quantum (NISQ) circuits.";
  
negative.code: { stdenv
  , lib
  , buildPythonPackage
  , pythonOlder
  , fetchFromGitHub
  