Add XY_7_2 plot

[andersy005]

Towards #3

• Original NCL:

• Python Version:

[erogluorhan]

Comparison of plots:

1. Python version should divide x-axis into 5 minor-ticks instead of 3 between adjacent major ticks (e.g. 1970.0 and 1970.5

2. Python plot is missing the very last curve change (which is the closest point to 1973.0) on the red dashed line plot that is apparent in NCL plot.

3. If identical dash-spaces with NCL plot is of interest, the following code:
   ax2.plot(ds.time, ds.P, color=color, linestyle=linestyle, linewidth=2.0)
   can be exchanged with the following one:
   ax2.plot(ds.time, ds.P, color=color, linestyle=linestyle, dashes=[6.5, 3.7], linewidth=2.0)

[erogluorhan]

Although explicit initialization of variables such as fontsize and labelsize contribute to the readability of the code since they are used as is in both plots, how about using variables such as color and linestyle with immediate values within plot codes instead of explicitly initializing them (because they have changing values for each plot)?

[andersy005]