code: def add_trendline(self,date0,date1,on='close',text=None,**kwargs):
  		
  		d={'kind':'trend','date0':date0,'date1':date1,'on':on,'text':text}
  		d.update(**kwargs)
  		self.trendlines.append(d)
docs: Adds a trendline to the QuantFigure. 
  		Given 2 dates, the trendline is connected on the data points
  		that correspond to those dates. 
  
  		Parameters:
  			date0 : string
  				Trendline starting date
  			date1 :  string
  				Trendline end date
  			on : string
  				Indicate the data series in which the 
  				trendline should be based.
  					'close'
  					'high'
  					'low'
  					'open'
  			text : string
  				If passed, then an annotation will be added 
  				to the trendline (at mid point)
  
  		kwargs:
  			from_strfmt : string
  				Defines the date formating in which 
  				date0 and date1 are stated. 
  				default: '%d%b%y'					
  			to_strfmt : string
  				Defines the date formatting 
  				to which it should be converted. 
  				This should match the same format as the timeseries index. 
  				default : '%Y-%m-%d'