<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def es_get_class_defs(cls_def, cls_name):
 """ Reads through the class defs and gets the related es class defintions Args: ----- class_defs: RdfDataset of class definitions """

    rtn_dict = {key: value for key, value in cls_def.items() \
                if key.startswith("kds_es")}
    for key in rtn_dict:
        del cls_def[key]
    return rtn_dict