According to this article a friend forwarded to me, software developers who learn Go, Python or Scala (along with tech like Apache Spark) have found it easier to find jobs with better salaries. Learning Scala caused the highest boost and in the second place was Go.
Learning python is a bit subjective in terms of getting a raise. It depends on what you are doing and which field you are in. So the increase in income with Python isn’t as consistent as it is with the other 2 languages.
Here is the article in detail: http://www.infoworld.com/article/3071623/salary/want-to-boost-your-salary-learn-scala-golang-or-python.html