how to define variable in .env code example

Example 1: how to set up env variable

npm install dotenv --save

Next add the following line to your app: "require('dotenv').config()"

Then create a .env file at the root directory of your application 
and add the variables to it.

Example 2: how to define environment variables

Use pm.environment to define an environment 
variable (in the currently selected environment):

pm.environment.set("variable_key", "variable_value");