commands: Created Option struct

commands/option.go

+package commands
+
+import "reflect"
+
+const (
+  Invalid = reflect.Invalid
+  Bool = reflect.Bool
+  Int = reflect.Int
+  Uint = reflect.Uint
+  Float = reflect.Float32
+  String = reflect.String
+)
+
+// Option is used to specify a field that will be provided by a consumer
+type Option struct {
+  Names []string      // a list of unique names to
+  Type reflect.Kind           // value must be this type
+  //Default interface{} // the default value (ignored if `Required` is true)
+  //Required bool       // whether or not the option must be provided
+}