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: help_command.rb
    path of file: ./repos/truffleruby/lib/mri/rubygems/commands
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
require_relative "../command"

class Gem::Commands::HelpCommand < Gem::Command
  # :stopdoc:
  EXAMPLES = <<-EOF
Some examples of 'gem' u
    
  def show_command_help(command_name) # :nodoc:
    command_name = command_name.downcase

    possibilities = @command_manager.find_command_possibilities command_name

    if possibilities.size == 1
      command = @command_manager[possibilities.first]
      command.invoke("--help")
    elsif possibilities.size > 1
      alert_warning "Ambiguous command #{command_name} (#{possibilities.join(', ')})"
    else
      alert_warning "Unknown command #{command_name}. Try: gem help commands"
    end