Why is this an issue?

break and continue are unstructured control flow statements which make code harder to read. Additionally, more recent versions of Python raise a SyntaxError when modules containing break or continue outside of a loop are imported.

Therefore, these statements should not be used outside of loops.

Noncompliant code example

narg=len(sys.argv)
if narg == 1:
        print('@Usage: input_filename nelements nintervals')
        break

Compliant solution

if narg == 1:
        print('@Usage: input_filename nelements nintervals')
        sys.exit()