pandas.DataFrame.pivot_table  cannot generate a correct Pivot Table for financial data of `General Ledger`.
## description 
As I have to cope with financial data, like an accountant, pivot table is a powerful tool for me.Yet recently, calling method `pandas.DataFrame.pivot_table`, I encountered a problem.
With data of `General Ledgers` (17 columns and over 7000 rows) I had expected to get a pivot table with values = `debit amount minus credit amount` for each `journal ID`, which identifies each `journal entry`, columns = `account name`, and index = `journal ID`. According to the `primary accounting equation`, for each `journal entry` we have `sum of debit amount` equal `sum of credit amount`. Thus, sum of all data of a big pivot table, whose index is `journal ID`, whose columns is `account name` and whose values are `debit minus credit`, must be zero.
However, when having called `pandas.DataFrame.pivot_table`, I found that sum of all data of that pivot table, did not equals zero. To be carefully, I generated a pivot table with `Microsoft Excel`, and it was no doubt that sum of whole pivot table equaled zero.
## code
Talk is cheap, here is the code.
```python
#!/usr/bin/env python
from pandas import read_excel
d=read_excel(excel_file_of_gl,sheet_name='Sheet1',header=0,engine='openpyxl')
d.pivot_table(values=['drcr'],index=['jid'],columns=['accna']).to_excel(./data.xlsx')
# 'drcr' means 'debit minus credit','jid' means 'journal id', and 'accna' means 'account name'.
# open the output file, sum of all the 'drcr' value did not equaled zero, which was weird.
```