'Return any spatial index creation SQL for the field.'

def sql_indexes_for_field(self, model, f, style):

    from django.contrib.gis.db.models.fields import GeometryField
    output = super(SpatiaLiteCreation, self).sql_indexes_for_field(model, f, style)
    if isinstance(f, GeometryField):
        gqn = self.connection.ops.geo_quote_name
        qn = self.connection.ops.quote_name
        db_table = model._meta.db_table
        output.append(((((((((((((((style.SQL_KEYWORD('SELECT    ') + style.SQL_TABLE('AddGeometryColumn')) + '(') + style.SQL_TABLE(gqn(db_table))) + ',    ') + style.SQL_FIELD(gqn(f.column))) + ',    ') + style.SQL_FIELD(str(f.srid))) + ',    ') + style.SQL_COLTYPE(gqn(f.geom_type))) + ',    ') + style.SQL_KEYWORD(str(f.dim))) + ',    ') + style.SQL_KEYWORD(str(int((not f.null))))) + ');'))
        if f.spatial_index:
            output.append(((((((style.SQL_KEYWORD('SELECT    ') + style.SQL_TABLE('CreateSpatialIndex')) + '(') + style.SQL_TABLE(gqn(db_table))) + ',    ') + style.SQL_FIELD(gqn(f.column))) + ');'))
    return output
