34 Execution control library [exec]

34.9 Senders [exec.snd]

34.9.6 execution​::​transform_sender [exec.snd.transform]

namespace std::execution { template<class Domain, sender Sndr, queryable... Env> requires (sizeof...(Env) <= 1) constexpr sender decltype(auto) transform_sender(Domain dom, Sndr&& sndr, const Env&... env) noexcept(see below); }
Let transformed-sndr be the expression dom.transform_sender(std::forward<Sndr>(sndr), env...) if that expression is well-formed; otherwise, default_domain().transform_sender(std::forward<Sndr>(sndr), env...)
Let final-sndr be the expression transformed-sndr if transformed-sndr and sndr have the same type ignoring cv-qualifiers; otherwise, it is the expression transform_sender(dom, transformed-sndr, env...).
Returns: final-sndr.
Remarks: The exception specification is equivalent to noexcept(final-sndr).