code: protected String getGeneSymbol(Match m, String label)
  	{
  		ProteinReference pr = (ProteinReference) m.get(label, getPattern());
  		return getGeneSymbol(pr);
  	}
docs: Searches for the gene symbol of the given EntityReference.
  @param m current match
  @param label label of the related EntityReference in the pattern
  @return symbol