def METHOD_NAME() -> None:
    from superset.db_engine_specs.oracle import OracleEngineSpec
    col = column("decimal")
    expr = OracleEngineSpec.get_timestamp_expr(col, None, "P1M")
    result = str(expr.compile(dialect=oracle.dialect()))
    assert result == "TRUNC(CAST(\"decimal\" as DATE), 'MONTH')"