class_docstr: This dataset describes a monthly count of the number of observed sunspots for
  just over 230 years (1749-1983).
  
  The units are a count and there are 2,820 observations. The source of the dataset is
  credited to Andrews & Herzberg (1985).
  
  References:
      .. [#1] Andrews, D. F. and Herzberg, A. M., "Data: A Collection of Problems from
          Many Fields for the Student and Research Worker,"
          New York: Springer-Verlag, 1985.
      .. [#2] https://stat.ethz.ch/R-manual/R-devel/library/datasets/html/sunspots.html
      .. [#3] https://r-data.pmagunia.com/dataset/r-dataset-package-datasets-sunspots
      .. [#4] Avishek Pal, PKS Prakash, "Practical Time Series Analysis"
          https://github.com/PacktPublishing/Practical-Time-Series-Analysis/
code: def _convert_to_date(self, val):
      month, year = math.modf(val)
      month = round(month * 12) + 1
      year = int(year)
      return "{}-{}".format(year, month)
  
file_path: AIX360/aix360/datasets/sunspots_dataset.py
imports: import os
  import math
  from io import StringIO
  import requests
  import pandas
label_desc: Use image node_id 2 for calling the SunspotDataset obj's underlying member method code with example usage: obj._convert_to_date(val) and returns: str