code: def dist_is_in_project(self, dist):
          
          from .project import _normalized
          prefixes = [
              _normalized(prefix) for prefix in self.base_paths["libdirs"].split(os.pathsep)
              if _normalized(prefix).startswith(_normalized(self.prefix.as_posix()))
          ]
          location = self.locate_dist(dist)
          if not location:
              return False
          location = _normalized(make_posix(location))
          return any(location.startswith(prefix) for prefix in prefixes)
docs: Determine whether the supplied distribution is in the environment.