Return the version of the AST library being used
"
2.0-7"
which contains integers representing the "
major version"
(2), the
"
minor version"
(0) and the "
release"
(7). The integer returned by this function combines all three
integers together into a single integer using the expresion:
(major version)∗1E6 + (minor version)∗1E3 + (release)