title: Python Class "Constants" in Dataclasses
body: <p>Understanding that the below are not true constants, attempting to follow <a href="https://www.python.org/dev/peps/pep-0008/#constants" rel="noreferrer">PEP 8</a> I'd like to make a "constant" in my @dataclass in Python 3.7.</p>
  
  <pre><code>@dataclass
  class MyClass:
      data: DataFrame
  
      SEED = 8675309  # Jenny's Constant
  </code></pre>
  
  <p>My code used to be:</p>
  
  <pre><code>class MyClass:
      SEED = 8675309  # Jenny's Constant
  
      def __init__(data):
          self.data = data
  </code></pre>
  
  <p>Are these two equivalent in there handling of the seed?  Is the seed now part of the init/eq/hash?  Is there a preferred style for these constants?</p>