<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def column_to_bq_schema(self):
 """Convert a column to a bigquery schema object. """

        kwargs = {}
        if len(self.fields) > 0:
            fields = [field.column_to_bq_schema() for field in self.fields]
            kwargs = {"fields": fields}

        return google.cloud.bigquery.SchemaField(self.name, self.dtype,
                                                 self.mode, **kwargs)