def epub_name(configuration_suffix = nil)
      epub_name = if !@book.output_base_name.nil?
                    @book.output_base_name
                  elsif @book.from_file?
                    ::File.basename(@book.file_path, ::File.extname(@book.file_path))
                  else
                    @book.title
                  end

      epub_name += @book.build_version.to_s unless @book.build_version.nil?
      epub_name += "-#{@target.name}" if @target != @book.default_target
      epub_name += "-#{configuration_suffix}" unless configuration_suffix.nil?
      epub_name + '.epub'
    end
def epub_name(configuration_suffix = nil)
      epub_name = if !@book.output_base_name.nil?
                    @book.output_base_name
                  elsif @book.from_file?
                    ::File.basename(@book.file_path, ::File.extname(@book.file_path))
                  else
                    @book.title
                  end

      epub_name += @book.build_version.to_s unless @book.build_version.nil?
      epub_name += "-#{@target.name}" if @target != @book.default_target
      epub_name += "-#{configuration_suffix}" unless configuration_suffix.nil?
      epub_name + '.epub'
    end
Creates name of epub file for current book and current target

 @return [String] name of result epub file