Returns a home-grown description that includes a summary of the calling interface
        for all the module procedures embedded in this interface.

def describe(self):
        """Returns a home-grown description that includes a summary of the calling interface
        for all the module procedures embedded in this interface.
        """
        #Interfaces are tricky because we can have an arbitrary number of embedded procedures
        #that each have different calling interfaces and return types. We are trying to 
        #summarize that information in a single interface. Interfaces can't mix executable
        #types; they are either all subroutines or all functions. 
        self.find_docstring()
        if not self.subroutine:
            #We have a return type to worry about, compile it from all the targets
            ret_type = []
            for target in self.targets:
                if target.returns not in ret_type:
                    ret_type.append(target.returns)

            ret_text = ', '.join(ret_type)
        else:
            ret_text = ""

        #The list of types it accepts is constructed the same way for functions and subroutines.
        act_type = []
        for target in self.targets:
            param = target.ordered_parameters[0]
            if param.strtype not in act_type:
                act_type.append(param.strtype)

        act_text = ', '.join(act_type)

        if self.subroutine:
            return "SUMMARY: {} | ACCEPTS: {}".format(self.summary, act_text)
        else:
            return "SUMMARY: {} | RETURNS: {} | ACCEPTS: {}".format(self.summary, ret_text, act_text)