code: def p_while_statement(self, p):
          'while_statement : WHILE LPAREN cond RPAREN whilecontent_statement'
          p[0] = WhileStatement(p[3], p[5], lineno=p.lineno(1))
          p.set_lineno(0, p.lineno(1)f p_while_statement(self, p):
          'while_statement : WHILE LPAREN cond RPAREN whilecontent_statement'
          p[0] = WhileStatement(p[3], p[5], lineno=p.lineno(1))
          p.set_lineno(0, p.lineno(1))
docs: while_statement : WHILE LPAREN cond RPAREN whilecontent_statement