code: def _update_value(config, key, instruction, is_sensitive):
      
      if config.has_option(PROFILE, key):
          current_value = config.get(PROFILE, key)
      else:
          current_value = None
  
      proposed = click.prompt(
          instruction,
          default=current_value,
          hide_input=is_sensitive,
          confirmation_prompt=is_sensitive,
      )
  
      if key == 'host' or key == 'prod_folder':
          if proposed[-1] == '/':
              proposed = proposed[:-1]
  
      if key == 'host':
          if 'http' != proposed[:4]:
              proposed = click.prompt(
                  ("looks like there's an issue - "
                   'make sure the host name starts with http'),
                  default=current_value,
                  hide_input=is_sensitive,
                  confirmation_prompt=is_sensitive,
              )
      config.set(PROFILE, key, proposed)
docs: creates (if needed)  and updates the value of the key in the config with a
       value entered by the user
  
      Parameters
      ----------
      config: ConfigParser object
          existing configuration
      key: string
          key to update
      instruction: string
          text to show in the prompt
      is_sensitive: bool
          if true, require confirmation and do not show typed characters
  
      Notes
      -----
      sets key in config passed in