<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def content_type(self):
 """ Get the CoRE Link Format ct attribute of the resource. :return: the CoRE Link Format ct attribute """

        value = ""
        lst = self._attributes.get("ct")
        if lst is not None and len(lst) > 0:
            value = "ct="
            for v in lst:
                value += str(v) + " "
        if len(value) > 0:
            value = value[:-1]
        return value