How to use the tabulate._table_formats.keys function in tabulate

    type=click.Choice(tabulate._table_formats.keys()),
    help='Table output style.')
@click.pass_obj
def report(globs: ROAttrDict, task: str, stats: bool, duration: str, sort: str,
           reverse: bool, style: str):
    """Report time tracking data.

    \f
    Args:
        globs: Global options object
        task: Task name to operate on
        stats: Display short overview of data
        duration: Time window to filter on
        sort: Key to sort events on
        reverse: Reverse sort order
        style: Table formatting style

# Hack to add some more formats.
# TODO: Add Graphite support.
# TODO: Remove padding.
tabulate._table_formats["csv"] = tabulate.TableFormat(
    lineabove=None,
    linebelowheader=None,
    linebetweenrows=None,
    linebelow=None,
    headerrow=tabulate.DataRow("", ";", ""),
    datarow=tabulate.DataRow("", ";", ""),
    padding=0,
    with_header_hide=None,
)

tabulate.tabulate_formats = list(sorted(tabulate._table_formats.keys()))


class Namespaces(object):
    r"""Helper for namespaces.

    The config file would look like:
    ```
    [carbon-relay]
    pattern = carbon\.relay\.*

    [carbon-cache]
    pattern = carbon\.agents\.*

    [carbon-aggregator]
    pattern = carbon\.aggregator\.*