reserve k,n for Nat,
  x,y,z,y1,y2 for object,X,Y for set,
  f,g for Function;
reserve p,q,r,s,t for XFinSequence;
reserve D for set;
reserve i for Nat;
reserve m for Nat,
        D for non empty set;
reserve l for Nat;

theorem
 <%x,y%> = (0,1) --> (x,y)
proof
A1: dom<%x,y%> = len<%x,y%>
    .= {0,1} by Th35,CARD_1:50;
A2: <%x,y%>.0 = x;
  <%x,y%>.1 = y;
 hence <%x,y%> = (0,1) --> (x,y) by A1,A2,FUNCT_4:66;
end;
