code: def where(self, field, value = None, operator = None):
          
          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
docs: Establece condiciones para la consulta unidas por AND