code: def format_rst(self):
          
          res = ''
          num_cols = len(self.header)
          col_width = 25
          for _ in range(num_cols):
              res += ''.join(['=' for _ in range(col_width - 1)]) + ' ' 
          res += '\n'
          for c in self.header:
              res += c.ljust(col_width) 
          res += '\n'
          for _ in range(num_cols):
              res += ''.join(['=' for _ in range(col_width - 1)]) + ' ' 
          res += '\n'
          for row in self.arr:
              for c in row:
                  res += self.force_to_string(c).ljust(col_width)
              res += '\n' 
          for _ in range(num_cols):
              res += ''.join(['=' for _ in range(col_width - 1)]) + ' ' 
          res += '\n'
          return res
docs: return table in RST format