code: def get_build_env(self):
          
          try:
              return self._memo['get_build_env']
          except KeyError:
              pass
  
          # Create the build environment instance with appropriate
          # overrides.  These get evaluated against the current
          # environment's construction variables so that users can
          # add to existing values by referencing the variable in
          # the expansion.
          overrides = {}
          for odict in self.overridelist:
              overrides.update(odict)
  
          import SCons.Defaults
          env = self.env or SCons.Defaults.DefaultEnvironment()
          build_env = env.Override(overrides)
  
          self._memo['get_build_env'] = build_env
  
          return build_env
docs: Fetch or create the appropriate build Environment
          for this Executor.