Using Python, use the implicit bml object in the Python dictionary and call the bmlExec() function:
bml.execBML('utah', '<head type="NOD"/>')
where utah is the name of the character, and the second parameter to the bmlExec function is the BML, described below. Note that using Python, commands can be specified using the single quote, instead of the double quote character, which is advisable, since most BML commands will contain many double quote character for use with attributes. Alternatively, you could specify BML using Python like this:
bml.execBML("utah", "<head type=\"NOD\"/>")
Notice that double quotes are used for the function parameters, while double quotes contained within the BML are escaped using the slash character.