def __init__(self, copy_from=None):
        """
        Parameters
        ----------
        copy_from : TargetConfig or None
            if None, creates an empty ``TargetConfig``.
            Otherwise, creates a copy.
        """
        self._values = {}
        if copy_from is not None:
            assert isinstance(copy_from, TargetConfig)
            self._values.update(copy_from._values)

        Parameters
        ----------
        copy_from : TargetConfig or None
            if None, creates an empty ``TargetConfig``.
            Otherwise, creates a copy.
        
numba/core/targetconfig.py