# Functions
IsDup check if err is mongo E11000 (duplicate err).
IsErrNoDocuments check if err is no documents, simply call if err == ErrNoSuchDocuments or if err == mongo.ErrNoDocuments.
NewObjectID generates a new ObjectID.
ObjectIDFromHex creates a new ObjectID from a hex string It returns an error if the hex string is not a valid ObjectID.
Open return database instance handler.
# Variables
ErrInvalidHex indicates that a hex string cannot be converted to an ObjectID.
ErrNoSuchDocuments return if no document found.
NilObjectID is the zero value for ObjectID.