'Returns the mount directory of \'module\'
:param module: desired module (memory, ...)
:return: mount directory of \'module\' or None'

def get_pwd(self, module):

    try:
        i = self.modules[0].index(module)
    except Exception as inst:
        logging.error('module    %s    not    found:    %s', module, inst)
        return None
    return self.modules[1][i]
