text: #ifndef TYPECHECK
  #define TYPECHECK
  
  #include "tree.h"
  
  int has_type_errors();
  void type_error(node_t* root);
  data_type_t typecheck_default(node_t* root);
  data_type_t typecheck_expression(node_t* root);
  data_type_t typecheck_assignment(node_t* root);
  data_type_t typecheck_variable(node_t* root);
  
  #endif
  