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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def loaded_instruments(self) -> Dict[str, Optional['InstrumentContext']]: """ Get the instruments that have been loaded into the protocol. :returns: A dict mapping mount names in lowercase to the instrument in that mount, or `None` if no instrument is present. """

        return {mount.name.lower(): instr for mount, instr
                in self._instruments.items()}