Using a string as an index of dataframe
#### Code Sample, a copy-pastable example if possible

temp = "['A', 'B']"
transactions[temp]

#### Problem description
I am trying to use a string as an index of dataframe. Here if I write **transactions[['A', 'B']]** the code runs ,but when I write the same thing into a string and pass it as an index it does not work.

#### Expected Output
I want to display a dataframe including both the columns.
