code: def _lookup_unconflicted_symbol(self, symbol):
          
          try:
              uppered = symbol.upper()
          except AttributeError:
              # The mapping fails because symbol was a non-string
              return numpy.nan
  
          try:
              return self.finder.lookup_symbol(
                  uppered,
                  as_of_date=None,
                  country_code=self.country_code,
              )
          except MultipleSymbolsFound:
              # Fill conflicted entries with zeros to mark that they need to be
              # resolved by date.
              return 0
          except SymbolNotFound:
              # Fill not found entries with nans.
              return numpy.nan
docs: Attempt to find a unique asset whose symbol is the given string.
  
          If multiple assets have held the given symbol, return a 0.
  
          If no asset has held the given symbol, return a  NaN.