class_docstr: Creates and manages a virtualenv for benchmarking, which allows for
  clean dependency management and benchmarking of multiple versions without
  contaminating the system's `site-packages` folder.
class_docstr_tok: ["Creates","and","manages","a","virtualenv","for","benchmarking",",","which","allows","for","clean","dependency","management","and","benchmarking","of","multiple","versions","without","contaminating","the","system","'s","`","site-packages","`","folder","."]
docstr: Activates the virtualenv at `VIRTUALENV_PATH`.
docstr_tok: ["Activates","the","virtualenv","at","`","VIRTUALENV_PATH","`","."]
code: def activate_virtualenv(self):
      """Activates the virtualenv at `VIRTUALENV_PATH`."""
      logging.info(
          "Activating virtualenv at: `{}`".format(self._virtualenv_path)
      )
      self._is_activated = True
      return ". {}/bin/activate".format(self._virtualenv_path)
  
imports: import logging
  import os
  import sys
  import signal
  import subprocess
  import venv
  import tornado
  from timeit import timeit
  from perspective import Table, PerspectiveManager, PerspectiveTornadoHandler
label_desc: Use image node_id 3 for calling the VirtualEnvHandler obj's underlying member method code with example usage: obj.activate_virtualenv() and returns: str