code: func (t Type) IsAlias() bool {
  	if t.IsMultipleInheritance() || t.IsArray() || t.IsUnion() || t.TypeString() == "object" {
  		return false
  	}
  	return t.TypeString() != "" && len(t.Properties) == 0
  }
docs: // IsAlias returns true if this Type is
  // alias of another Type