Obtaining/compiling/installing python3.7

[Richard Owlett]

I wish to try some beta software which assumes python3.7 is installed. I 
have Debian 9.8 installed on a machine dedicated to this exercise. I did 
a web search and got a half dozen on topic hits. There were enough 
differences that I wasn't sure if I was missing something important. The 
last time I compiled something was on a PDP 11/45 in approximately 1975.

Suggestions?
TIA