You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: bindings.rb
    path of file: ./repos/rdkafka-ruby/lib/rdkafka
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Rdkafka
  # @private
  module Bindings
    extend FFI::Library

    def self.lib_extension
      if RbConfig::CONFIG['host_os'] =~ /darwin/
  
    
    def self.partitioner(str, partition_count, partitioner_name = "consistent_random")
      # Return RD_KAFKA_PARTITION_UA(unassigned partition) when partition count is nil/zero.
      return -1 unless partition_count&.nonzero?

      str_ptr = str.empty? ? FFI::MemoryPointer::NULL : FFI::MemoryPointer.from_string(str)
      method_name = PARTITIONERS.fetch(partitioner_name) do
        raise Rdkafka::Config::ConfigError.new("Unknown partitioner: #{partitioner_name}")
      end
      public_send(method_name, nil, str_ptr, str.size > 0 ? str.size : 1, partition_count, nil, nil)
    end