Both answers are correct.
append() by default adds your argument to the end of the list. It's throwing a syntax error as you are passing it 2 arguments and it is only accepting 1.
Judging by your syntax you want your path added to the front of the path so insert() is the method to use.
You can read more in the documentation on Data Structures
list.append(x)
Add an item to the end of the list; equivalent to
a[len(a):] = [x].
list.insert(i, x)
Insert an item at a given position. The first
argument is the index of the element before which to insert, so
a.insert(0, x) inserts at the front of the list, and a.insert(len(a),
x) is equivalent to a.append(x).
import sys
# Inserts at the front of your path
sys.path.insert(0, "/path/to/module/abc.py")
# Inserts at the end of your path
sys.path.append('/path/to/module/abc.py')
insertinstead ofappend, but the fact that you are getting aSyntaxError(not aTypeErrormeans that you have a typo somewhere (unclosed parenthesis or something).