How to get img src in string in selenium using python

I have a google search result, something like

div class="rc"
    h3 class="r"
        <a href="somelink">
            <img id="idFOO" src="data:somethingFOO" style="...">
        </a>

I want to add somethingFOO (or data:somethingFOO) to a string using python & selenium. How can I do that?