code: def add(self, loan_id, amount):
          
          assert amount > 0 and amount % 25 == 0, 'Amount must be a multiple of 25'
          assert type(amount) in (float, int), 'Amount must be a number'
  
          if type(loan_id) is dict:
              loan = loan_id
              assert 'loan_id' in loan and type(loan['loan_id']) is int, 'loan_id must be a number or dictionary containing a loan_id value'
              loan_id = loan['loan_id']
  
          assert type(loan_id) in [str, unicode, int], 'Loan ID must be an integer number or a string'
          self.loans[loan_id] = amount
docs: Add a loan and amount you want to invest, to your order.
          If this loan is already in your order, it's amount will be replaced
          with the this new amount
  
          Parameters
          ----------
          loan_id : int or dict
              The ID of the loan you want to add or a dictionary containing a `loan_id` value
          amount : int % 25
              The dollar amount you want to invest in this loan, as a multiple of 25.