```ruby
# Prompt configuration

brice 'prompt' => nil do |config|

  class IRB::Context
    %w[prompt_i prompt_s prompt_c prompt_n return_format].each { |name|
      define_method(name) {
        ivar = instance_variable_get("@#{name}")
        ivar.respond_to?(:call) ? ivar['%.4f' % @runtime] : ivar
      }
    }

    alias_method :_brice_original_evaluate, :evaluate

    # Capture execution time
    def evaluate(line, line_no)
      @runtime = Benchmark.realtime { _brice_original_evaluate(line, line_no) }
    end
  end

  IRB.conf[:PROMPT] ||= {}  # prevent error in webrick

  IRB.conf[:PROMPT][:BRICE] = {                   # name of prompt mode
    :PROMPT_I => '  ',                            # normal prompt
    :PROMPT_S => '  ',                            # prompt for continuing strings
    :PROMPT_C => '  ',                            # prompt for continuing statement
    :RETURN   => lambda { |rt| "#{rt} => %s\n" }  # format to return value
  }

  IRB.conf[:PROMPT_MODE] = :BRICE

end
```

Set different default prompt under Ruby 1.9.
user
```ruby
# Prompt configuration

brice 'prompt' => nil do |config|

  class IRB::Context
    %w[prompt_i prompt_s prompt_c prompt_n return_format].each { |name|
      define_method(name) {
        ivar = instance_variable_get("@#{name}")
        ivar.respond_to?(:call) ? ivar['%.4f' % @runtime] : ivar
      }
    }

    alias_method :_brice_original_evaluate, :evaluate

    # Capture execution time
    def evaluate(line, line_no)
      @runtime = Benchmark.realtime { _brice_original_evaluate(line, line_no) }
    end
  end

  IRB.conf[:PROMPT] ||= {}  # prevent error in webrick

  # prompt configuration:
  #
  #   PROMPT_I = normal prompt
  #   PROMPT_S = prompt for continuing strings
  #   PROMPT_C = prompt for continuing statement
  #   RETURN   = format to return value

  IRB.conf[:PROMPT].update(
    :BRICE_SIMPLE => {
      :PROMPT_I => '  ',
      :PROMPT_S => '  ',
      :PROMPT_C => '  ',
      :RETURN   => lambda { |rt| "#{rt} => %s\n" }
    },
    :BRICE_VERBOSE => {
      :PROMPT_I => "#{RUBY_VERSION}p#{RUBY_PATCHLEVEL}> ",
      :PROMPT_S => "#{RUBY_VERSION}p#{RUBY_PATCHLEVEL}> ",
      :PROMPT_C => "#{RUBY_VERSION}p#{RUBY_PATCHLEVEL}> ",
      :RETURN   => lambda { |rt| "#{rt} => %s\n" }
    }
  )

  IRB.conf[:PROMPT_MODE] = RUBY_VERSION < '1.9' ? :BRICE_SIMPLE : :BRICE_VERBOSE

end
```
assistant