code: def preprocess(self):
          '''
          Performs initial cell conversions to standard types. This will strip units, scale numbers,
          and identify numeric data where it's convertible.
          '''
          self.processed_tables = []
          self.flags_by_table = []
          self.units_by_table = []
          for worksheet, rtable in enumerate(self.raw_tables):
              ptable, flags, units = self.preprocess_worksheet(rtable, worksheet)
              self.processed_tables.append(ptable)
              self.flags_by_table.append(flags)
              self.units_by_table.append(units)
  
          return self.processed_tablef preprocess(self):
          '''
          Performs initial cell conversions to standard types. This will strip units, scale numbers,
          and identify numeric data where it's convertible.
          '''
          self.processed_tables = []
          self.flags_by_table = []
          self.units_by_table = []
          for worksheet, rtable in enumerate(self.raw_tables):
              ptable, flags, units = self.preprocess_worksheet(rtable, worksheet)
              self.processed_tables.append(ptable)
              self.flags_by_table.append(flags)
              self.units_by_table.append(units)
  
          return self.processed_tables
docs: Performs initial cell conversions to standard types. This will strip units, scale numbers,
          and identify numeric data where it's convertible.