def prepend(key, bins, options = nil)
      policy = create_policy(options, WritePolicy, default_write_policy)
      command = WriteCommand.new(@cluster, policy, key, hash_to_bins(bins), Aerospike::Operation::PREPEND)
      execute_command(command)
    end
def prepend(key, bins, options = nil)
      policy = create_policy(options, WritePolicy, default_write_policy)
      command = WriteCommand.new(@cluster, policy, key, hash_to_bins(bins), Aerospike::Operation::PREPEND)
      execute_command(command)
    end
Prepends bin values string to existing record bin values.
  The policy specifies the transaction timeout, record expiration and
  how the transaction is handled when the record already exists.

  This call works only for string values.

  If no policy options are provided, +@default_write_policy+ will be used.
  Examples:

  client.prepend key, {'bin', 'value to prepend'}, :timeout => 0.001