What use is of this 'cast=float ,'?

[Robert]

Hi,

I read below code snippet on line. I am interested in the second of the last 
line.

     cast=float ,


I've tried it in Python. Even simply with 

float


it has no error, but what use is it?


I do see a space before the comma ','. Is it a typo or not?


Thanks,



self.freqslider=forms.slider(
     parent=self.GetWin( ),
     sizer=freqsizer,
     value=self.freq,
     callback= self.setfreq,
     minimum=−samprate/2,
     maximum=samprate/2,
     num_steps=100,
     style=wx.SL_HORIZONTAL,
     cast=float ,
     proportion=1,
)