arcgis desktop - Using python to convert string values with Calculate Field in ModelBuilder?

In ArcGIS 10.5, I am building a model that should convert a field of coded values to another code. This seems like it should be a simple if/then statement but I am not getting it. To simplify the process, I populated the target field with the source field's values and then intend on using python to transpose the values. It should be considered a string, but the values are numerical. The field I am trying to edit is "TP_Condi"

In the "Calculate Field" code block:

def reclass:  
if TP_Condi = 3:    
     return 1    
elif TP_Condi = 2:     
     return 8  
elif TP_Condi = 1:    
     return 3  
else:    
     return "error" 

---

This is the code I was seeking: