Hello!

I am working on a text mining project that requires input text to be in a specific format. The initial text comes from Reddit, where the original poster (OP) is starting a new topic and then other people (commenters) reply to the OP. An exemplar data format is provided below:
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str11 user str5 comment
"OP"          "text1"
"commenter_1" "text2"
"commenter_2" "text3"
"commenter_3" "text4"
"commenter_4" "text5"
"commenter_5" "text6"
end
For the purpose of my analysis, the data need to be pre-processed as conversation turns, a type of organization in conversation where participants speak one at a time in alternating turns. In case of Reddit, however, it is not always the case that the OP replies to the commenters (as is in the example above). Therefore, I need to add a new line with user = OP and comment = "" (blanc) after each commenter's response. For example:
Code:
"OP"          "text1"
"commenter_1" "text2"
"OP"          ""
"commenter_2" "text3"
"OP"          ""
"commenter_3" "text4"
"OP"          ""
"commenter_4" "text5"
"OP"          ""
"commenter_5" "text6"
"OP"          ""
/*Note that some commenters might provide multiple responses*/
Can you please help me solve this problem.