docs: def exists(self, symbol):
          """Checks to if a symbol exists, by name.
          
          Parameters
          ----------
          symbol : str or Symbol
  
          Returns
          -------
          bool
          """
  
          if isinstance(symbol, str):
              sym = symbol
          elif isinstance(symbol, Symbol):
              sym = symbol.name
  
          syms = self.ses.query(Symbol).filter(Symbol.name == sym).all()
          if len(syms) == 0:
              return False
          else:
              return True