Print language name of the code chunks, with knitr html?

Heyy, I want to print out the "language name" of the code chunk but couldn't figure it out. I'm using these settings, pretty much default:

    toc: true
    number_sections: false
    theme: simplex
    highlight: tango
    df_print: page


Can we indicate what language is the block, python or r, in the output document? Hopefully with a simple parameter that we can configure in front-matter.

How about you manually add R and Python comments in the code chunks so that you are able to see them in the final output?