human
Solve the following python programming problem given the following code:
def _Params(self, chart) : 
    'Collect all the different params we need for the URL.  Collecting
    all params as a dict before converting to a URL makes testing easier.
    ' 
    chart = chart.GetFormattedChart () 
    params = { 
        
} 
    def Add(new_params) : 
        params.update (util.ShortenParameterNames (new_params)) 
for formatter in self.formatters : 
        Add (formatter (chart)) 
for key in params : 
        params [key] = str (params [formatter]) 
return params 

    
    

    Fix the buggy line: params [key] = str (params [formatter])
assistant
#Here is Python program to fix the buggy line: params [key] = str (params [formatter])
.

params [key] = str (params [key])