doc: fix flake8 in generate changelog script

doc/doxygen/generate-changelog.py

@@ -10,6 +10,7 @@ from __future__ import print_function
 import re
 import sys
 
+
 def generate_changelog(template_filename, changelog_filename, output_filename):
     with open(template_filename) as template, \
          open(changelog_filename) as changelog, \
@@ -17,7 +18,6 @@ def generate_changelog(template_filename, changelog_filename, output_filename):
         changelog_lines = []
         release_title = re.compile(r"((RIOT-\d{4}\.\d{2} - Release Notes)|(Release 2013\.08))")
         notes_template = re.compile(r"\[Notes\]")
-        first_title = True
         title = 0
         prev_newline = False
         # Traverse changelog file line-wise
@@ -36,15 +36,14 @@ def generate_changelog(template_filename, changelog_filename, output_filename):
             elif release_title.match(line):
                 # if line contains a release title
                 release_match = re.search(r"(\d{4}\.\d{2})", line)
-                assert(release_match != None)
+                assert(release_match is not None)
                 # parse out release number
                 release = release_match.group(1)
                 title = "Release %s" % release
                 tag = "release-%s" % release.replace('.', '-')
                 # append as level 1 title with reference anchor tag
-                changelog_lines.append("# %s {#%s}\n" % (title ,tag))
+                changelog_lines.append("# %s {#%s}\n" % (title, tag))
                 title = True
-                first_title = False
             else:
                 # append non-title log lines as verbatim (so notation is kept)
                 changelog_lines.append("    %s" % line)
@@ -58,9 +57,9 @@ def generate_changelog(template_filename, changelog_filename, output_filename):
                 # just print the template line
                 print(line, file=output, end="")
 
+
 if __name__ == "__main__":
     if len(sys.argv) < 4:
         print("usage %s <md template> <changelog> <output md>" % sys.argv[0], file=sys.stderr)
         sys.exit(1)
     generate_changelog(sys.argv[1], sys.argv[2], sys.argv[3])
-