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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 _format_src_url(self, path, caller_system):
 """ Ensure path is absolute and use the correct URL format for use with cross Azure storage account copy function. Args: path (str):
 Path or URL. caller_system (pycosio.storage.azure._AzureBaseSystem subclass):
 System calling this method (Can be another Azure system). Returns: str: URL. """

        path = '%s/%s' % (self._endpoint, self.relpath(path))

        # If SAS token available, use it to give cross account copy access.
        if caller_system is not self:
            try:
                path = '%s?%s' % (path, self._storage_parameters['sas_token'])
            except KeyError:
                pass

        return path