title: dict from dataclass returns empty dictionary
body: <p>I'm new to dataclasses and am trying to make a simple way to convert one to a dictionary with I can then save and load from a JSON file. Before I implement the infrastructure I need for my application, I'm testing it on a small dataclass with the variables I'll be working with which is below:</p>
  <pre><code>from dataclasses import dataclass, asdict
  @dataclass 
  class TestClass:
      def __init__(self, floatA:[float], intA:[int], floatB:[float]):
          self.var1 = floatA
          self.var2 = intA
          self.var3 = floatB
  
      def ConvertToDict(self):
          return asdict(self)
  
  test = TestClass([0.2,0.1,0.5], [1,2,3], [0.9,0.7,0.6])
  print(asdict(test))
  print(test.ConvertToDict())
  </code></pre>
  <p>Both print statements are an empty dictionary '{}' and I can't seem to figure out why</p>