C: 1: 9: Prefer double-quoted strings unless you need single quotes
to avoid extra backslashes for escaping.
C: 4: 7: Prefer double-quoted strings unless you need single quotes
to avoid extra backslashes for escaping.
C: 5: 11: Prefer double-quoted strings unless you need single quotes
to avoid extra backslashes for escaping.
C: 6: 12: Prefer double-quoted strings unless you need single quotes
to avoid extra backslashes for escaping.
C: 17: 7: Use %r around regular expression.
C: 19: 18: Prefer double-quoted strings unless you need single quotes
to avoid extra backslashes for escaping.
C: 20: 18: Prefer double-quoted strings unless you need single quotes
to avoid extra backslashes for escaping.