code: def update_version_number(update_level='patch'):
      
  
      """Find current version"""
      temp_file = version_file().parent / ("~" + version_file().name)
      with open(str(temp_file), 'w') as g:
          with open(str(version_file()), 'r') as f:
              for line in f:
                  version_matches = bare_version_re.match(line)
                  if version_matches:
                      bare_version_str = version_matches.groups(0)[0]
                      if semantic_version.validate(bare_version_str):
                          current_version = Version(bare_version_str)
                          print("{}Current version is {}".format(" "*4, current_version))
                      else:
                          current_version = Version.coerce(bare_version_str)
                          if not text.query_yes_quit("{}I think the version is {}. Use it?".format(" "*4, current_version), default="yes"):
                              exit(Fore.RED + 'Please set an initial version number to continue')
  
                      """Determine new version number"""
                      if update_level is 'major':
                          current_version = current_version.next_major()
                      elif update_level is 'minor':
                          current_version = current_version.next_minor()
                      elif update_level is 'patch':
                          current_version = current_version.next_patch()
                      elif update_level is 'prerelease':
                          if not current_version.prerelease:
                              current_version = current_version.next_patch()
                              current_version.prerelease = ('dev', )
                      else:
                          exit(Fore.RED + 'Cannot update version in {} mode'.format(update_level))
  
                      print("{}New version is     {}".format(" "*4, current_version))
  
                      """Update version number"""
                      line = '__version__ = "{}"'.format(current_version)
                  print(line, file=g, end="")
          print('', file=g)  # add a blank line at the end of the file
      shutil.copyfile(str(temp_file), str(version_file()))
      os.remove(str(temp_file))
      return(current_version)
docs: Update version number
  
      Returns a semantic_version object