nullptr 6 src/core/Compartment.cpp , neuron(nullptr) nullptr 16 src/core/Compartment.cpp voxel -> set_compartment(nullptr); nullptr 135 src/core/Compartment.cpp voxel -> set_compartment(nullptr); nullptr 13 src/core/Network.cpp neuron -> set_network(nullptr); nullptr 73 src/core/Network.cpp return nullptr; nullptr 96 src/core/Network.cpp neuron -> set_network(nullptr); nullptr 6 src/core/Neuron.cpp , network(nullptr) nullptr 20 src/core/Neuron.cpp return nullptr; nullptr 29 src/core/Neuron.cpp compartment -> set_neuron(nullptr); nullptr 149 src/core/Neuron.cpp compartment -> set_neuron(nullptr); nullptr 5 src/core/Voxel.cpp , compartment(nullptr)