jupyter lab extensions not working code example

Example: jupyter lab extensions not working

jupyter_client            6.1.0                      py_0    anaconda
jupyter_contrib_core      0.3.3                      py_2    conda-forge
jupyter_contrib_nbextensions 0.5.1                    py37_0    conda-forge
jupyter_core              4.6.1                    py37_0    anaconda
jupyter_highlight_selected_word 0.2.0                 py37_1000    conda-forge
jupyter_latex_envs        1.4.4                 py37_1000    conda-forge
jupyter_nbextensions_configurator 0.4.1                    py37_0    conda-forge
jupyterlab                2.0.1                      py_0    conda-forge
jupyterlab_server         1.0.7                      py_0    conda-forge
...
nodejs                    13.10.1              h38d8c5a_0    conda-forge