deffunc H₄( Nat) -> Element of HFuncs NAT = In ((m const $1),(HFuncs NAT));
consider f being Function of NAT,(HFuncs NAT) such that
A1: for n being Element of NAT holds f . n = H₄(n) from FUNCT_2:sch 4();
take f ; :: thesis: for n being Nat holds f . n = m const n
let n be Nat; :: thesis: f . n = m const n
n in NAT by ORDINAL1:def 12;
hence f . n = H₄(n) by A1
.= m const n by COMPUT_1:31, SUBSET_1:def 8 ;
:: thesis: verum