backslash before comma in the Sep argument

Hi Asmaa!
Thanks for reaching out.

In Python, a backslash (\) before characters like a comma in the sep argument of

 pandas.read_csv()

is used to escape special characters.
A raw string in Python, denoted by prefixing the string with an r, tells Python to treat the backslash (\) as a literal character and not as an escape character. For example,

 r"\n"

will be treated as the characters \ and n, not as a newline character. Raw strings are useful for paths and regular expressions where backslashes frequently appear.

Hope this helps.
Best,
Tsvetelin