code: def resolve(self, symbol):
          
  
          # Try the variables first
          if symbol in self.variables:
              return self.variables[symbol]
  
          return self.policy.resolve(symbol)
docs: Resolve a symbol encountered during a rule evaluation into the
          actual value for that symbol.
  
          :param symbol: The symbol being resolved.
  
          :returns: The value of that symbol.  If the symbol was not
                    declared in the ``variables`` parameter of the
                    constructor, a call will be made to the ``Policy``'s
                    ``resolve()`` method.