the principle of "constellation modulator"?

Recently I was learning the working principle of "constellation modulator". I read the file "generic_mod_demod.py" and realized that it is a hierarchical block. I was confused about its working principle, why there is no other action after it is connected to rrc_filter. What? Shouldn't the general IQ modulation have "acoswt-bsinwt" or "(a + bi) exp(-jwt)" operation? I haven't seen similar operations in the code, but the output of the "constellation modulator" is a baseband complex modulated signal. Is there anything else I can't see?

mod code:

        # Connect

        self._blocks = [self, self.bytes2chunks]

        if self.pre_diff_code:

            self._blocks.append(self.symbol_mapper)

        if differential:

            self._blocks.append(self.diffenc)

        self._blocks += [self.chunks2symbols, self.rrc_filter, self]

        self.connect(*self._blocks)