<SYSTEM_TASK:>
Given the following text description, write Python code to implement the functionality described below step by step
<END_TASK>
<USER_TASK:>
Description:
 Bar plot demo
This example shows you how to make a bar plot using the psyplot.project.ProjectPlotter.barplot method.
Step1:  The default is that all bars have the same width. You can however change that by setting
the widths keyword to data
Step2:  Or you make a stacked plot
<ASSISTANT_TASK:>
Python Code:
import psyplot.project as psy
%matplotlib inline
%config InlineBackend.close_figures = False
axes = iter(psy.multiple_subplots(2, 2, n=3))
for var in ['t2m', 'u', 'v']:
    psy.plot.barplot(
        'demo.nc',  # netCDF file storing the data
        name=var, # one plot for each variable
        y=[0, 1],  # two bars in total
        z=0, x=0,      # choose latitude and longitude as dimensions
        ylabel="{desc}",  # use the longname and units on the y-axis
        ax=next(axes),
        color='coolwarm', xticklabels='%B %Y',
        legendlabels='latitude %(y)1.2f $^\circ$N', legend='upper left',
        title='equally spaced'
    )
bars = psy.gcp(True)
bars.show()
Explanation: Bar plot demo
This example shows you how to make a bar plot using the psyplot.project.ProjectPlotter.barplot method.
End of explanation
bars(name='u').update(widths='data', xticks='month', title='data spaced')
bars.show()
Explanation: The default is that all bars have the same width. You can however change that by setting
the widths keyword to data
End of explanation
bars(name='v').update(plot='stacked', title='stacked')
bars.show()
psy.close('all')
Explanation: Or you make a stacked plot
End of explanation
<END_TASK>