code: def ensure_workspace(self, target):
      
      gopath = self.get_gopath(target)
      for d in ('bin', 'pkg', 'src'):
        safe_mkdir(os.path.join(gopath, d))
      required_links = set()
      for dep in target.closure():
        if not isinstance(dep, GoTarget):
          continue
        if self.is_remote_lib(dep):
          self._symlink_remote_lib(gopath, dep, required_links)
        else:
          self._symlink_local_src(gopath, dep, required_links)
      self.remove_unused_links(os.path.join(gopath, 'src'), required_links)
docs: Ensures that an up-to-date Go workspace exists for the given target.
  
      Creates any necessary symlinks to source files based on the target and its transitive
      dependencies, and removes any symlinks which do not correspond to any needed dep.