def combine(pubkeys)
      raise ArgumentError, 'must give at least 1 pubkey' if pubkeys.empty?

      outpub = FFI::Pubkey.new.pointer
      #pubkeys.each {|item| }

      res = C.secp256k1_ec_pubkey_combine(@ctx, outpub, pubkeys, pubkeys.size)
      raise AssertError, 'failed to combine public keys' unless res == 1

      @public_key = outpub
      outpub
    end
def combine(pubkeys)
      raise ArgumentError, 'must give at least 1 pubkey' if pubkeys.empty?

      outpub = FFI::Pubkey.new.pointer
      #pubkeys.each {|item| }

      res = C.secp256k1_ec_pubkey_combine(@ctx, outpub, pubkeys, pubkeys.size)
      raise AssertError, 'failed to combine public keys' unless res == 1

      @public_key = outpub
      outpub
    end
Add a number of public keys together.