test/first (#8)

Introducing first very simple tests for tools.py

Reviewed-on: https://www.kuhl-mann.de/git/git/jkuhl/corrlib/pulls/8

corrlib/tools.py

@@ -2,24 +2,24 @@ import os
 import datalad.api as dl
 
 
-def str2list(string):
+def str2list(string: str):
     return string.split(",")
 
 def list2str(mylist):
     s = ",".join(mylist)
     return s
 
-cached = True
+cached: bool = True
 
-def m2k(m):
+def m2k(m: float) -> float:
     return 1/(2*m+8)
 
 
-def k2m(k):
+def k2m(k: float) -> float:
     return (1/(2*k))-4
 
 
-def get_file(path, file):
+def get_file(path: str, file: str):
     if file == "backlogger.db":
         print("Downloading database...")
     else: