def parse_issuance_p2sh_pointer(script_sig)
      script = Bitcoin::Script.new(script_sig).chunks.last
      redeem_script = Bitcoin::Script.new(script)
      return nil unless redeem_script.chunks[1] == Bitcoin::Script::OP_DROP
      asset_def = to_bytes(redeem_script.chunks[0].to_s.bth)[0..-1].map{|x|x.to_i(16).chr}.join
      asset_def && asset_def.start_with?('u=') ? asset_def : nil
    end
def parse_issuance_p2sh_pointer(script_sig)
      script = Bitcoin::Script.new(script_sig).chunks.last
      redeem_script = Bitcoin::Script.new(script)
      return nil unless redeem_script.chunks[1] == Bitcoin::Script::OP_DROP
      asset_def = to_bytes(redeem_script.chunks[0].to_s.bth)[0..-1].map{|x|x.to_i(16).chr}.join
      asset_def && asset_def.start_with?('u=') ? asset_def : nil
    end
parse issuance p2sh which contains asset definition pointer