docs: def read_price_data(files, name_func=None):
      """
      Convenience function for reading in pricing data from csv files
  
      Parameters
      ----------
      files: list
          List of strings refering to csv files to read data in from, first
          column should be dates
      name_func: func
          A function to apply to the file strings to infer the instrument name,
          used in the second level of the MultiIndex index. Default is the file
          name excluding the pathname and file ending,
          e.g. /path/to/file/name.csv -> name
  
      Returns
      -------
      A pandas.DataFrame with a pandas.MultiIndex where the top level is
      pandas.Timestamps and the second level is instrument names. Columns are
      given by the csv file columns.
      """
      if name_func is None:
          def name_func(x):
              return os.path.split(x)[1].split(".")[0]
  
      dfs = []
      for f in files:
          name = name_func(f)
          df = pd.read_csv(f, index_col=0, parse_dates=True)
          df.sort_index(inplace=True)
          df.index = pd.MultiIndex.from_product([df.index, [name]],
                                                names=["date", "contract"])
          dfs.append(df)
  
      return pd.concat(dfs, axis=0, sort=False).sort_index()