import re  
def text_match(text):  
        patterns = '^[a-zA-Z0-9_]*$'  
        if re.search(patterns,  text):  
                return 'Found a match!'  
        else:  
                return('Not matched!')  
  
print(text_match("The quick brown fox jumps over the lazy dog."))  
print(text_match("Python_Exercises_1"))