code: def activate_cython(self):
          
          run_cython = os.environ.get("SPY_RUN_CYTHON") == "True"
  
          if run_cython:
              try:
                  __import__('Cython')
                  self.has_cython = True
              except Exception:
                  pass
  
              if self.has_cython:
                  # Import pyximport to enable Cython files support for
                  # import statement
                  import pyximport
                  pyx_setup_args = {}
  
                  # Add Numpy include dir to pyximport/distutils
                  try:
                      import numpy
                      pyx_setup_args['include_dirs'] = numpy.get_include()
                  except Exception:
                      pass
  
                  # Setup pyximport and enable Cython files reload
                  pyximport.install(setup_args=pyx_setup_args,
                                    reload_support=True)
docs: Activate Cython support.
  
          We need to run this here because if the support is
          active, we don't to run the UMR at all.