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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 delete_custom_field(self, custom_field_key):
 """Deletes a custom field associated with this list."""

        custom_field_key = quote(custom_field_key, '')
        response = self._delete("/lists/%s/customfields/%s.json" %
                                (self.list_id, custom_field_key))