Hash declaration in Scilla

gistfile1.txt

contract Hash()

field a: Option ByStr32 = None {ByStr32} (*declaring variable a with no value*)
field b: ByStr32 = 0x123456789012345678901234567890123456789012345678901234567890abff
(*declaring variable b with some fixed value*)

transition update_value()

   (*updating variable a*)
   c = 0xabff567890123456789012345678901234567890123456789012345678901234; (*declaring variable c with fixed value in the transition*)
   tmp= Some {ByStr32} c;
   a:= tmp;
    
   (*updating variable b*)
   d= 0xffff567890123456789012345678901234567890123456789012345678901234;
   b:= d
     
end