module Asciidoctor::Helpers

def self.require_library(name)

value of delegating to Kernel#require
returns false if the library is detected on the load path or the return

name - the String name of the library to require.

manual require if running in a threaded environment.
Internal: Prior to invoking Kernel#require, issues a warning urging a 
def self.require_library(name)
  if Thread.list.size > 1
    main_script = "#{name}.rb"
    main_script_path_segment = "/#{name}.rb"
    if !$LOADED_FEATURES.detect {|p| p == main_script || p.end_with?(main_script_path_segment) }.nil?
      return false
    else
      warn "WARN: asciidoctor is autoloading '#{name}' in threaded environment. " +
         "The use of an explicit require '#{name}' statement is recommended."
    end
  end
  require name
end