class Avm::Git::Scms::GitSubtree

def valid?
  return false unless ::Avm::Git::Scms::Provider
                      .new.all.any? { |scm_class| parent_scm.is_a?(scm_class) }
  (::Avm::Git::Scms::Provider.new.all - [self.class])
    .lazy.map { |scm_class| scm_class.new(path) }.none?(&:valid?)
end