code: def series(self, x: str, y: list, title: str = '') -> object:
          
  
          code = "proc sgplot data=" + self.libref + '.' + self.table + self._dsopts() + ";\n"
          if len(title) > 0:
              code += '\ttitle "' + title + '";\n'
  
          if isinstance(y, list):
              num = len(y)
          else:
              num = 1
              y = [y]
  
          for i in range(num):
              code += "\tseries x=" + x + " y=" + str(y[i]) + ";\n"
  
          code += 'run;\n' + 'title;'
  
          if self.sas.nosub:
              print(code)
              return
  
          ll = self._is_valid()
          if not ll:
              html = self.HTML
              self.HTML = 1
              ll = self.sas._io.submit(code)
              self.HTML = html
          if not self.sas.batch:
              self.sas.DISPLAY(self.sas.HTML(ll['LST']))
          else:
              return ll
docs: This method plots a series of x,y coordinates. You can provide a list of y columns for multiple line plots.
  
          :param x: the x axis variable; generally a time or continuous variable.
          :param y: the y axis variable(s), you can specify a single column or a list of columns
          :param title: an optional Title for the chart
          :return: graph object