Establece condiciones para la consulta unidas por AND

def where(self, field, value = None, operator = None):
        """
        Establece condiciones para la consulta unidas por AND
        """
        if field is None:
            return self
        conjunction = None
        if value is None and isinstance(field, dict):
            for f,v in field.items():
                if self.where_criteria.size() > 0:
                    conjunction = 'AND'
                self.where_criteria.append(expressions.ConditionExpression(f, v, operator=operator, conjunction=conjunction))
                
        else:
            if self.where_criteria.size() > 0:
                    conjunction = 'AND'
            self.where_criteria.append(expressions.ConditionExpression(field, value, operator=operator, conjunction=conjunction))
        return self