import re
   
this1 = "hello.del"
   
try:
    this2 = re.sub("\.del$","\.e\nn\\c",this1)
    # why is the \\ not a valid escape of backslash
    # how do I escape a backslash?
except:
    print("with the \\\\c failed")
   
this2 = re.sub("\.del$","\.e\nnc",this1)
    #why is the \. not an escaped . ?
   
print(this2)