title: Preserve quotes and also add data with quotes in Ruamel
body: <p>I am using Ruamel to preserve quote styles in human-edited YAML files.</p>
  
  <p>I have example input data as:</p>
  
  <pre><code>---
  a: '1'
  b: "2"
  c: 3
  </code></pre>
  
  <p>I read in data using:</p>
  
  <pre><code>def read_file(f):
      with open(f, 'r') as _f:
          return ruamel.yaml.round_trip_load(_f.read(), preserve_quotes=True)
  </code></pre>
  
  <p>I then edit that data:</p>
  
  <pre><code>data = read_file('in.yaml')
  data['foo'] = 'bar'
  </code></pre>
  
  <p>I write back to disk using:</p>
  
  <pre><code>def write_file(f, data):
      with open(f, 'w') as _f:
          _f.write(ruamel.yaml.dump(data, Dumper=ruamel.yaml.RoundTripDumper, width=1024))
  
  write_file('out.yaml', data)
  </code></pre>
  
  <p>And the output file is:</p>
  
  <pre><code>a: '1'
  b: "2"
  c: 3
  foo: bar
  </code></pre>
  
  <p>Is there a way I can enforce hard quoting of the string 'bar' without also enforcing that quoting style throughout the rest of the file?</p>
  
  <p>(Also, can I stop it from deleting the three dashes <code>---</code> ?)</p>