code: def p_statement_while(p):
      'statement : WHILE LPAREN expr RPAREN while_statement'
      p[0] = ast.While(p[3], p[5], lineno=p.lineno(1)f p_statement_while(p):
      'statement : WHILE LPAREN expr RPAREN while_statement'
      p[0] = ast.While(p[3], p[5], lineno=p.lineno(1))
docs: statement : WHILE LPAREN expr RPAREN while_statement