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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 _get_vswitch_for_physical_network(self, phys_network_name):
 """Get the vswitch name for the received network name."""

        for pattern in self._physical_network_mappings:
            if phys_network_name is None:
                phys_network_name = ''
            if re.match(pattern, phys_network_name):
                return self._physical_network_mappings[pattern]