added come comments

pkg.go

@@ -6,36 +6,54 @@ import (
 	"runtime"
 )
 
+// Assert evalueates a condition and if it fails, panics.
 func Assert(cond bool, msg string) {
-	if cond {
+	if !cond {
 		panic(errors.New(msg))
 	}
 }
 
-func Check(cond bool, err error) *invariants {
+// Check evaluates a condition, adds an error to its list and continues
+func Check(cond bool, err error) I {
 	return new(invariants).Check(cond, err)
 }
 
+// func ExampleCheck() {
+
+// }
+
+type I interface {
+	Check(cond bool, err error) I
+	Join() error
+	First() error
+	All() []error
+}
 type invariants struct {
 	errs []error
 }
 
-func (i *invariants) Check(cond bool, err error) *invariants {
+// Check evaluates a condition, adds an error to its list and continues
+func (i *invariants) Check(cond bool, err error) I {
 	if !cond {
 		i.errs = append(i.errs, err)
 	}
 	return i
 }
 
+// Join returns all an error wrapping all errors that have been seen by the checks
 func (i *invariants) Join() error {
 	return errors.Join(i.errs...)
 }
+
+// First returns the first error found by the checks
 func (i *invariants) First() error {
 	if len(i.errs) > 0 {
 		return i.errs[0]
 	}
 	return nil
 }
+
+// All returns all errors found by the checks as a list of errors
 func (i *invariants) All() []error {
 	return i.errs
 }
@@ -60,6 +78,7 @@ func (e *xError) Unwrap() error {
 	return e.E
 }
 
+// NewError return an error that wrapped an error and optionally provides the file and line number the error occured on
 func NewError(unwrapped error, debug bool) error {
 	_, file, line, ok := runtime.Caller(1)