def get_metadata(self, signature=None):
        """
        Obtain the compilation metadata for a given signature.
        """
        if signature is not None:
            return self.overloads[signature].metadata
        else:
            return dict(
                (sig,self.overloads[sig].metadata) for sig in self.signatures
            )

        Obtain the compilation metadata for a given signature.
        
numba/core/dispatcher.py