refactor: added assert statement

Author: arteevraina

integration_tests/func_internal_def_01.py

@@ -4,7 +4,7 @@ def main():
     print(x)
 
     def bar():
-        print("bar")
+        assert x == 25
 
     bar()
 

src/lpython/semantics/python_ast_to_asr.cpp

@@ -4281,6 +4281,7 @@ class SymbolTableVisitor : public CommonVisitor<SymbolTableVisitor> {
         } else {
             bool is_pure = false, is_module = false;
 
+            // This checks for internal function defintions as well.
             for (size_t i = 0; i < x.n_body; i++) {
                 visit_stmt(*x.m_body[i]);
             }