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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 dst_to_src(self, dst_file):
 """Map destination path to source URI."""

        for map in self.mappings:
            src_uri = map.dst_to_src(dst_file)
            if (src_uri is not None):
                return(src_uri)
        # Must have failed if loop exited
        raise MapperError(
            "Unable to translate destination path (%s) "
            "into a source URI." % (dst_file))