new_contents: import pandas as pd
  
  # Cumulative entries and exits for one station for a few hours.
  entries_and_exits = pd.DataFrame({
      'ENTRIESn': [3144312, 3144335, 3144353, 3144424, 3144594,
                   3144808, 3144895, 3144905, 3144941, 3145094],
      'EXITSn': [1088151, 1088159, 1088177, 1088231, 1088275,
                 1088317, 1088328, 1088331, 1088420, 1088753]
  })
  
  def get_hourly_entries_and_exits(data):
      '''
      takes a DataFrame with cumulative entries
      and exits, returns a DataFrame with hourly entries and exits.
      '''
  
      return (data - data.shift(periods=1)).drop(0)
  
  print get_hourly_entries_and_exits(entries_and_exits)
  
subject: Create hourly_entries.py