code: public void addExportable(String name, BtrpOperand e, Set<String> scopes) {
          this.exported.put(name, e);
          this.exportScopes.put(name, scopes);
      }
docs: Add an external operand that can be accessed from several given scopes.
  A scope is a namespace that can ends with a wildcard ('*'). In this situation. The beginning
  of the scope is considered
  
  @param name   the name of the exported operand
  @param e      the operand to add
  @param scopes the namespaces of the scripts that can use this variable. {@code null} to allow anyone