Fix validation error type `GL01` and check in CI

[MarckK]

Problem description

In order to have a continuous check by the CI on validation error GL01 (Docstring text, i.e. summary, should start in the line immediately after the opening quotes, not in the same line, or leaving a blank line in between), fixing them in the code base enables the addition to the CI for automated testing in the future.

GL01 has 189 occurrences (see overview of the errors), including:

method	file	file_line	github_link
pandas.Timestamp	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.max	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.min	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.ctime	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.date	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.dst	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.isocalendar	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.isoweekday	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.strftime	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.strptime	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.time	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.timestamp	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.timetuple	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.timetz	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.to_datetime64	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.toordinal	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.tzname	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.utcoffset	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.utctimetuple	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timestamp.weekday	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timedelta.components	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timedelta.days	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timedelta.microseconds	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timedelta.seconds	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timedelta.view	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Timedelta.to_timedelta64	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Interval.left	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Interval.length	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Interval.right	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Categorical.codes	pandas/core/arrays/categorical.py	676.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/arrays/categorical.py#L676
...	...	...	...
pandas.plotting.lag_plot	pandas/plotting/_misc.py	570.0	https://github.com/pandas-dev/pandas/blob/master/pandas/plotting/_misc.py#L570
pandas.plotting.parallel_coordinates	pandas/util/_decorators.py	454.0	https://github.com/pandas-dev/pandas/blob/master/pandas/util/_decorators.py#L454
pandas.core.resample.Resampler.pipe	pandas/core/resample.py	189.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L189
pandas.core.resample.Resampler.first	pandas/core/resample.py	857.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L857
pandas.core.resample.Resampler.last	pandas/core/resample.py	857.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L857
pandas.core.resample.Resampler.max	pandas/core/resample.py	857.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L857
pandas.core.resample.Resampler.min	pandas/core/resample.py	857.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L857
pandas.core.resample.Resampler.prod	pandas/core/resample.py	846.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L846
pandas.core.resample.Resampler.sum	pandas/core/resample.py	846.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/resample.py#L846
pandas.Series.index	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Series.T	pandas/core/base.py	672.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/base.py#L672
pandas.Series.dt.dayofweek	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.weekday	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_month_start	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_month_end	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_quarter_start	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_quarter_end	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_year_start	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_year_end	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.Series.dt.is_leap_year	pandas/core/accessor.py	80.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/accessor.py#L80
pandas.io.formats.style.Styler.env	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.io.formats.style.Styler.template	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.io.formats.style.Styler.loader	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Series.ix	pandas/core/indexing.py	1385.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/indexing.py#L1385
pandas.DataFrame.ix	pandas/core/indexing.py	1385.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/indexing.py#L1385
pandas.Panel.items	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Panel.ix	pandas/core/indexing.py	1385.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/indexing.py#L1385
pandas.Panel.keys	pandas/core/generic.py	1824.0	https://github.com/pandas-dev/pandas/blob/master/pandas/core/generic.py#L1824
pandas.Panel.major_axis	None	NaN	https://github.com/pandas-dev/pandas/blob/master/None#LNone
pandas.Panel.minor_axis

Todo:

• get rid of the errors in the code base
• update the code_check.sh script to take into account the GL01 type of errors

[zangell44]

i can pick this up if no one's already started

[zangell44]

how should external documentation be handled?

for example, the documentation for pandas.io.formats.style.Styler.env comes directly from jinja2.Environment:

"The core component of Jinja is the Environment. It contains
important shared variables like configuration, filters, tests,
globals and others. Instances of this class may be modified if
they are not shared and if no template was loaded so far.
Modifications on environments after the first template was loaded
will lead to surprising effects and undefined behavior.

Here are the possible initialization parameters:

`block_start_string`
    The string marking the beginning of a block.  Defaults to ``'{%'``.

`block_end_string`
    The string marking the end of a block.  Defaults to ``'%}'``.

...
bytecode_cache
If set to a bytecode cache object, this object will provide a
cache for the internal Jinja bytecode so that templates don't
have to be parsed if they were not changed.

    See :ref:`bytecode-cache` for more information.

`enable_async`
    If set to true this enables async template execution which allows
    you to take advantage of newer Python features.  This requires
    Python 3.6 or later."

would you like me to override the existing documentation, removing the newline character at the beginning of the string?

[nickagian]

I have encountered similar case for the SS03 validation errors. I think we should have a common approach to this.

[dcreekp]

the Timestamp and Timedelta errors overlaps with a pull request I've made, which is also stalled for similar reasons:
#25118 (comment)