Modifying escape sequences in strings

[Thomas Philips]

I have been playing around with reading strings with embedded escape
sequences from files both using readline() and codecs.open() and have
a question.I create a file "test.txt" with exactly one line:
1\na\n\n2\n\n3

I then open test.txt and then read it using readline():
>>> input_file=file("test.txt")
>>> x=input_file.readline()

>>> x
>>> 1\\na\\n\\n2\\n\\n3
>>> print x
>>> 1\na\n\n2\n\n3

The readline has escaped the backslashes, so that they print
correctly. I tried to replace the double backslashes with single
backslashes to escape the "n"
>>> x.replace("\\","\")
	  
SyntaxError: EOL while scanning single-quoted string
>>> 

How can I replace the escaped backslash with a backslash? I realize
that I can solve the problem by reading the file using
codecs.open("test.txt","r","string_escape") as suggested by Peter
Otten. I'm trying to do the same thing in different ways to better
understand Python

Sincerely
Thomas Philips