solc v0.5.2 on my system, but I have several contracts, that require
solc < v0.5, so that I get errors:
Error: Source file requires different compiler version
What is the best way to run and choose between multiple versions of
solc v0.4.25, rename it into e.g.
solc04 and move it into
/usr/bin/? Or is there something like virtual environments for