def_extend_command

# File lib/irb/extend-command.rb, line 237
    def self.def_extend_command(cmd_name, load_file, *aliases)
      line = __LINE__; Context.module_eval %[
        def #{cmd_name}(*opts, &b)
          Context.module_eval {remove_method(:#{cmd_name})}
          require "#{load_file}"
          send :#{cmd_name}, *opts, &b
        end
        for ali in aliases
          alias_method ali, cmd_name
        end
      ], __FILE__, line
    end