在YAML中，我不断收到以下关于多行字符串的错误消息：

这是我的代码

operator_prompt: > 
What operation would you like to perform? 
1) add 
2) subtract 
3) multiple
4) divide

/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:377:in `parse': (calculator_messages.yml): could not find expected ':' while scanning a simple key at line 14 column 1 (Psych::SyntaxError)
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:377:in `parse_stream'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:325:in `parse'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:252:in `load'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in `block in load_file'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in `open'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in `load_file'
        from calculator.rb:2:in `<main>'

这是我的错误消息

operator_prompt: > 
What operation would you like to perform? 
1) add 
2) subtract 
3) multiple
4) divide

/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:377:in `parse': (calculator_messages.yml): could not find expected ':' while scanning a simple key at line 14 column 1 (Psych::SyntaxError)
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:377:in `parse_stream'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:325:in `parse'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:252:in `load'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in `block in load_file'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in `open'
        from /usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in `load_file'
        from calculator.rb:2:in `<main>'

/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:377:in'parse'：（calculator_messages.yml）：在扫描第14行第1列的简单键时找不到预期的“：”（psych:：SyntaxError）
from/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:377:in'parse_stream'
from/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:325:in'parse'
from/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:252:in'load'
from/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in'block in load_file'
from/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in'open'
from/usr/local/rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/psych.rb:471:in'load_file'
来自计算器。rb:2:in`'

---

我不知道是什么问题。看起来我在YAML中使用了多行字符串，这与我应该使用的完全一样。

您应该将折叠的多行标量缩进至少一个位置。如果要保留标量中的新行，请使用

：

operator_prompt: | 
  What operation would you like to perform? 
  1) add 
  2) subtract 
  3) multiple
  4) divide