code: def add(self, dist):
          
          new_path = (
              dist.location not in self.paths and (
                  dist.location not in self.sitedirs or
                  # account for '.' being in PYTHONPATH
                  dist.location == os.getcwd()
              )
          )
          if new_path:
              self.paths.append(dist.location)
              self.dirty = True
          Environment.add(self, dist)
docs: Add `dist` to the distribution map