code: def figure_naming(pretitle='', posttitle='', prefile='', postfile=''):
      
      if pretitle:
          pretitle = "%s -- " % pretitle
  
      if posttitle:
          posttitle = " -- %s" % posttitle
  
      if prefile:
          prefile = "%s_" % prefile
  
      if postfile:
          postfile = "_%s" % postfile
  
      return pretitle, posttitle, prefile, postfile
docs: Helper function to define the strings that handle pre-post conventions
      for viewing - plotting title and saving options.
  
      Args:
          pretitle(str): String to include before the general title of the figure.
          posttitle(str): String to include after the general title of the figure.
          prefile(str): String to include before the general filename of the figure.
          postfile(str): String to include after the general filename of the figure.
  
      Returns:
          str: String to include in the figure name and title, in a suitable form.