Method get_env

include/exec/fork_join.hpp:198–201

      STDEXEC_ATTRIBUTE(nodiscard, host, device)
      constexpr auto get_env() const noexcept -> _env_t
      {
        return STDEXEC::__fwd_env(STDEXEC::get_env(_rcvr_));
      }

      Rcvr                                         _rcvr_;
      _variant_t<_child_completions_t>             _cache_;