docs: def describe(self):
          """ describes a Symbol, returns a string """
          lines = []
          lines.append("Symbol = {}".format(self.name))
          if len(self.tags):
              tgs = ", ".join(x.tag for x in self.tags)
              lines.append("  tagged = {}".format(tgs))
          if len(self.aliases):
              als = ", ".join(x.alias for x in self.aliases)
              lines.append("  aliased = {}".format(als))
          if len(self.feeds):
              lines.append("  feeds:")
  
              for fed in self.feeds:
                  lines.append("    {}. {}".format(fed.fnum,
                                                         fed.ftype))
          return "\n".join(lines)