code: def write_case_data(self, file):
          
  #        title = "Power Flow Solution"
  #        file.write("=" * len(title))
  #        file.write("\n")
  #        file.write("\n%s\n" % title)
  #        file.write("=" * len(title))
  #        file.write("\n")
  
          # Document subtitle.
          subtitle = self.case.name
          file.write("-" * len(subtitle))
          file.write("\n%s\n" % subtitle)
          file.write("-" * len(subtitle))
          file.write("\n")
  
          file.write("System Summary\n")
          file.write("-" * 14)
          file.write("\n")
  
          self.write_how_many(file)
          self.write_how_much(file)
          self.write_min_max(file)
docs: Writes the header to file.