MAINT: Adds symbol to the list of api_methods.

zipline/algorithm.py

@@ -486,6 +486,15 @@ class TradingAlgorithm(object):
         for name, value in chain(positionals, iteritems(kwargs)):
             self._recorded_vars[name] = value
 
+    @api_method
+    def symbol(self, symbol_str, as_of_date=None):
+        """
+        Default symbol lookup for any source that directly maps the
+        symbol to the identifier (e.g. yahoo finance).
+        Keyword argument as_of_date is ignored.
+        """
+        return symbol_str
+
     @api_method
     def order(self, sid, amount,
               limit_price=None,