Add all the files from the interpreter repo

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

pkg/ast/string.go

@@ -0,0 +1,16 @@
+package ast
+
+import "code.jmug.me/jmug/interpreter-in-go/pkg/token"
+
+type StringLiteral struct {
+	Token token.Token
+	Value string
+}
+
+func (s *StringLiteral) expressionNode() {}
+func (s *StringLiteral) TokenLiteral() string {
+	return s.Token.Literal
+}
+func (s *StringLiteral) String() string {
+	return s.Token.Literal
+}