Are you talking about multi-line strings? Easy, use triple quotes to start and end them.
s = """ this is a very long string if I had the energy to type more and more ..."""
You can use single quotes too (3 of them of course at start and end) and treat the resulting string
s just like any other string.
NOTE : Just as with any string, anything between the starting and ending quotes becomes part of the string, so this example has a leading blank (as pointed out by @root45). This string will also contain both blanks and newlines.
' this is a very\n long string if I had the\n energy to type more and more ...'
Finally, one can also construct long lines in Python like this:
s = ("this is a very" "long string too" "for sure ..." )
which will not include any extra blanks or newlines (this is a deliberate example showing what the effect of skipping blanks will result in):
'this is a verylong string toofor sure ...'
No commas required, simply place the strings to be joined together into a pair of parenthesis and be sure to account for any needed blanks and newlines.