def camel_to_snake(text):  
        import re  
        str1 = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', text)  
        return re.sub('([a-z0-9])([A-Z])', r'\1_\2', str1).lower()  
  
print(camel_to_snake('PythonExercises'))