docs: def p_top_statement_namespace(p):
      '''top_statement : NAMESPACE namespace_name SEMI
                       | NAMESPACE LBRACE top_statement_list RBRACE
                       | NAMESPACE namespace_name LBRACE top_statement_list RBRACE'''
      if len(p) == 4:
          p[0] = ast.Namespace(p[2], [], lineno=p.lineno(1))
      elif len(p) == 5:
          p[0] = ast.Namespace(None, p[3], lineno=p.lineno(1))
      else:
          p[0] = ast.Namespace(p[2], p[4], lineno=p.lineno(1))