NewConstraints returns a Constraints instance that a Version instance can be checked against.

NewVersion parses a given version and returns an instance of Version or an error if unable to parse the version.

ErrInvalidConstraint is returned when a constraint is not valid.

ErrInvalidGoVersion is returned when a go version is not valid.

Constraints is one of more constraint that a go version can be checked against.

Version represents a single go version.

Collection is a collection of Version instances and implements the sort interface.