text: """
  * Assignment: DataFrame Groupby Astro Flights
  * Complexity: medium
  * Lines of code: 5 lines
  * Time: 13 min
  
  English:
      1. Read data from `DATA` as `df: pd.DataFrame`
      2. Create ranking of the most experienced astronauts (number of flights)
      3. Run doctests - all must succeed
  
  Polish:
      1. Wczytaj dane z `DATA` jako `df: pd.DataFrame`
      2. Stwórz ranking najbardziej doświadczonych astronautów (liczba lotów)
      3. Uruchom doctesty - wszystkie muszą się powieść
  
  Tests:
      >>> import sys; sys.tracebacklimit = 0
  
      >>> pd.set_option('display.width', 500)
      >>> pd.set_option('display.max_columns', 10)
      >>> pd.set_option('display.max_rows', 10)
  
      # >>> assert result is not Ellipsis, \
      # 'Assign result to variable: `result`'
      # >>> assert type(result) is pd.DataFrame, \
      # 'Variable `result` must be a `pd.DataFrame` type'
  
      >>> result  # doctest: +NORMALIZE_WHITESPACE
      Ellipsis
  
  TODO: Doctests
  """
  
  import pandas as pd
  
  
  result = ...
  
  
  