hello everyone , I have observed something strange The lines print('$!/\\@$@!') and print('$!/\@$@!') are yielding same result . Can someone say why can this happen.

Answer 1

You just discovered that the backlash (\) character escapes some characters, that otherwise have a special meaning.
For more information read this please:

https://learnpythonthehardway.org/book/ex10.html

Answer 2

Because backslash hints Python to expect a 'special escape sequence'. When one is not found (@ is not special), it dumps both \ and @.

Compare:

>>> print('\\\\')
\\
>>> print('\\\\ \@')
\\ \@
>>> print('\\\\ \n')
\\
<----- \n is "newline" (empty line here)
>>>

Learn Python The Hard Way (Escape Sequences section):

https://learnpythonthehardway.org/book/ex10.html

Answer 3

if that is the case, the output of the first statement must be $!/\@$@! and that of second must be $!/@$@!, right?