<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_last_transverse_over_list(self, zxq):
 """ Get transverse coord at highest z :param zx: A list where each element is (z, transverse, charge) """

        z_max = None
        x_of_interest = None

        for z, x, q in zxq:
            if z == None or z > z_max:
                x_of_interest = x

        return x_of_interest