docs: def try_to_get(self, symbol):
          """ Gets a Symbol based on name, which may or may not exist.
          
          Parameters
          ----------
          symbol : str
          
          Returns
          -------
          Symbol or None.  
          
          Note
          ----
          Use .get(), if the symbol should exist, and an exception 
          is needed if it doesn't.
  
          """
          syms = self.ses.query(Symbol).filter(Symbol.name == symbol).all()
          if len(syms) == 0:
              return None
          else:
              return syms[0]