Command help does not print help.

[qimingj]

For example, %%bigquery sample --help:

---

usage: bigquery sample [-h] [-q QUERY | -t TABLE | -v VIEW]
[-d {legacy,standard}] [-b BILLING] [-c COUNT]
[-m {limit,random,hashed,sorted}] [-p PERCENT]
[-f FIELD] [-o {ascending,descending}] [-P] [--verbose]

optional arguments:
-h, --help show this help message and exit
-q QUERY, --query QUERY
the name of the query to sample
...

But it does not display the help message:

"
Display a sample of the results of a BigQuery SQL query. The cell can
optionally contain arguments for expanding variables in the query, if
-q/--query was used, or it can contain SQL for a query.
"