code: def _update_version(self):
          
          #current = self.vcs.version
          current = self.data['new_version']
  
          # Clean it up to a non-development version.
          current = utils.cleanup_version(current)
          # Try to make sure that the suggestion for next version after
          # 1.1.19 is not 1.1.110, but 1.1.20.
          current_split = current.split('.')
          major = '.'.join(current_split[:-1])
          minor = current_split[-1]
          try:
              minor = int(minor) + 1
              suggestion = '.'.join([major, str(minor)])
          except ValueError:
              # Fall back on simply updating the last character when it is
              # an integer.
              try:
                  last = int(current[-1]) + 1
                  suggestion = current[:-1] + str(last)
              except ValueError:
                  logger.warn("Version does not end with a number, so we can't "
                              "calculate a suggestion for a next version.")
                  suggestion = None
          print("Current version is %r" % current)
          q = "Enter new development version ('.dev0' will be appended)"
          version = utils.ask_version(q, default=suggestion)
          if not version:
              version = suggestion
          if not version:
              logger.error("No version entered.")
              sys.exit()
  
          self.data['new_version'] = version
          dev_version = self.data['dev_version_template'] % self.data
          self.data['dev_version'] = dev_version
          logger.info("New version string is %r",
                      dev_version)
  
          self.vcs.version = self.data['dev_version']
docs: Ask for and store a new dev version string.