text: """
  29. How to replace missing spaces in a string with the least frequent character?
  """
  """
  Replace the spaces in my_str with the least frequent character.
  """
  """
  Difficiulty Level: L2
  """
  """
  Input
  """
  """
  my_str = 'dbc deb abed gade'
  """
  """
  Desired Output
  """
  """
  'dbccdebcabedcgade'  # least frequent is 'c'
  """
  