Add support for function/methods invocation on Environment + create call stack model

modules/lang/src/main/kotlin/io/smnp/ext/lang/LangModule.kt

@@ -1,7 +1,7 @@
 package io.smnp.ext.lang
 
-import io.smnp.callable.function.Function
 import io.smnp.ext.ModuleDefinition
+import io.smnp.ext.lang.function.DebugFunction
 import io.smnp.ext.lang.method.ListAccessMethod
 import io.smnp.ext.lang.method.MapAccessMethod
 import org.pf4j.Extension
@@ -10,7 +10,7 @@ import org.pf4j.Extension
 class LangModule : ModuleDefinition {
     override fun modulePath() = "smnp.lang"
 
-    override fun functions() = emptyList<Function>()
+    override fun functions() = listOf(DebugFunction())
 
     override fun methods() = listOf(ListAccessMethod(), MapAccessMethod())
 }

modules/lang/src/main/kotlin/io/smnp/ext/lang/function/DebugFunction.kt

@@ -0,0 +1,15 @@
+package io.smnp.ext.lang.function
+
+import io.smnp.callable.function.Function
+import io.smnp.callable.function.FunctionDefinitionTool
+import io.smnp.callable.signature.Signature.Companion.simple
+import io.smnp.type.model.Value
+
+class DebugFunction : Function("debug") {
+    override fun define(new: FunctionDefinitionTool) {
+        new function simple() define { env, _ ->
+            env.printCallStack()
+            Value.void()
+        }
+    }
+}