code: def earliest_possible_date():
      """
      The earliest date for which we can load data from this module.
      """
      today = pd.Timestamp("now", tz="UTC").normalize()
      # Bank of Canada only has the last 10 years of data at any given time.
      return today.replace(year=today.year - 10)
  
file_path: catalyst/catalyst/data/treasuries_can.py
imports: import pandas
  import six
  from toolz import curry
  from toolz.curried.operator import add
label_desc: Use image node_id 4 for calling a global function with example usage: earliest_possible_date() and returns: today