Using "variable" in plotly.express functions not documented in docstrings

• Usage of "variable" for such arguments as facet_col is not documented in the docstrings.
• For online examples of this feature see https://plotly.com/python/wide-form/.
• An extract of the docstring for px.line is below.
• plotly.__version__: 4.14.3

facet_row: str or int or Series or array-like
    Either a name of a column in `data_frame`, or a pandas Series or
    array_like object. Values from this column or array_like are used to
    assign marks to facetted subplots in the vertical direction.
facet_col: str or int or Series or array-like
    Either a name of a column in `data_frame`, or a pandas Series or
    array_like object. Values from this column or array_like are used to
    assign marks to facetted subplots in the horizontal direction.
facet_col_wrap: int
    Maximum number of facet columns. Wraps the column variable at this
    width, so that the column facets span multiple rows. Ignored if 0, and
    forced to 0 if `facet_row` or a `marginal` is set.
facet_row_spacing: float between 0 and 1
    Spacing between facet rows, in paper units. Default is 0.03 or 0.0.7
    when facet_col_wrap is used.
facet_col_spacing: float between 0 and 1
    Spacing between facet columns, in paper units Default is 0.02.