reassign values

ast/ast.go

@@ -379,3 +379,29 @@ func (we *WhileExpression) String() string {
 
 	return out.String()
 }
+
+// AssignmentStatement the `=` statement represents the AST node that rebinds
+// an expression to an identifier (assigning a new value).
+type AssignmentStatement struct {
+	Token token.Token // the token.ASSIGN token
+	Name  *Identifier
+	Value Expression
+}
+
+func (as AssignmentStatement) TokenLiteral() string {
+	return as.Token.Literal
+}
+
+func (as AssignmentStatement) String() string {
+	var out bytes.Buffer
+
+	out.WriteString(as.Name.String())
+	out.WriteString(as.TokenLiteral() + " ")
+	out.WriteString(as.Value.String())
+
+	out.WriteString(";")
+
+	return out.String()
+}
+
+func (as AssignmentStatement) statementNode() {}