title: pyyaml and using quotes for strings only
body: <p>I have the following YAML file:</p>
  
  <pre><code>---
  my_vars:
    my_env: "dev"
    my_count: 3
  </code></pre>
  
  <p>When I read it with PyYAML and dump it again, I get the following output:</p>
  
  <pre><code>---
  my_vars:
    my_env: dev
    my_count: 3
  </code></pre>
  
  <p>The code in question:</p>
  
  <pre><code>with open(env_file) as f:
      env_dict = yaml.load(f)
      print(yaml.dump(env_dict, indent=4, default_flow_style=False, explicit_start=True))
  </code></pre>
  
  <p>I tried using the <code>default_style</code> parameter:</p>
  
  <pre><code>with open(env_file) as f:
      env_dict = yaml.load(f)
      print(yaml.dump(env_dict, indent=4, default_flow_style=False, explicit_start=True, default_style='"'))
  </code></pre>
  
  <p>But now I get:</p>
  
  <pre><code>---
  "my_vars":
    "my_env": "dev"
    "my_count": !!int "3"
  </code></pre>
  
  <p>What do I need to do to keep the original formatting, <strong>without</strong> making any assumptions about the variable names in the YAML file?</p>